Journal articles: 'Plasmalema'

1

ISHIKAWA, Harunori. "Plasmalemmal undercoat: The cytoskeleton supporting the plasmalemma." Archives of Histology and Cytology 51, no. 2 (1988): 127–45. http://dx.doi.org/10.1679/aohc.51.127.

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2

Peters, K. R., W. W. Carley, and G. E. Palade. "Endothelial plasmalemmal vesicles have a characteristic striped bipolar surface structure." Journal of Cell Biology 101, no. 6 (December 1, 1985): 2233–38. http://dx.doi.org/10.1083/jcb.101.6.2233.

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Capillary endothelial cells have a large population of small (65-80 nm diameter in transmission electron microscopy) vesicles of which a large fraction is associated with the plasmalemma of the luminal and abluminal side. We studied the fine structure and distribution of these plasmalemmal vesicles by high resolution scanning electron microscopy in cultured endothelial cells obtained from bovine adrenal cortical capillaries. Cell monolayers were covered with polylysine-coated silicon chips, split in high potassium buffer, fixed in aldehyde mixtures, and then treated with OsO4 and thiocarbohydrazide. After critical point drying, the specimens were coated with a thin (less than 2 nm) continuous film of chromium. On the cytoplasmic aspect of the dorsal plasmalemmal fragments seen in such specimens, plasmalemmal vesicles appear as uniform vesicular protrusions approximately 70-90 nm in diameter, preferentially concentrated in distinct large fields in which they occur primarily as single units. Individual plasmalemmal vesicles exhibit a striped surface fine structure which consists of ridges approximately 10 nm in diameter, separated by furrows and oriented as meridians, often ending at two poles on opposite sides of the vesicles in a plane parallel to the plasmalemma. This striped surface structure is clearly distinct from the cage structure of coated pits found, at low surface density, on the same specimens. The cytoplasmic aspect of the plasmalemma proper is covered by a fibrillar infrastructure which does not extend over plasmalemmal vesicles but on which the latter appear to be anchored by fine filaments.

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Kordylewski, L., T. Karrison, and E. Page. "Measurements on the internal structure of freeze-fractured cardiac plasma membrane." American Journal of Physiology-Heart and Circulatory Physiology 248, no. 3 (March 1, 1985): H297—H304. http://dx.doi.org/10.1152/ajpheart.1985.248.3.h297.

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We describe a quantitative analysis of the internal structure of cardiac plasma membranes freeze fractured in situ, including the P-face particle density (lambda), the P-face particle diameter (d), the percent of fracture face area occupied by particles (Ap), and the spatial distribution of particles (random, clustered, or ordered). This analysis has been applied to seven sheep hearts to compare the plasmalemmal internal structures in ventricular and atrial myocytes and Purkinje strands of the same hearts and also to myocytes of frog, chicken, rabbit, and rat ventricles (to compare internal plasmalemmal structure of different vertebrate classes). Measurements were made on tissues conventionally prepared for freeze fracture by glutaraldehyde fixation and cryoprotection. We found that, in the same sheep hearts, lambda and Ap for ventricular plasmalemma significantly exceeded those for atrial plasmalemma and that the distribution of atrial P-face particles was more clustered than that for ventricle. d and Ap for frog ventricular plasmalemmal P-face significantly exceeded values for some of the other vertebrates.

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4

Façanha, Arnoldo Rocha, Anna Lvovna Okorokova Façanha, Fábio Lopes Olivares, Fernando Guridi, Gabriel de Araújo Santos, Ary Carlos Xavier Velloso, Victor Marcos Rumjanek, et al. "Bioatividade de ácidos húmicos: efeitos sobre o desenvolvimento radicular e sobre a bomba de prótons da membrana plasmática." Pesquisa Agropecuária Brasileira 37, no. 9 (September 2002): 1301–10. http://dx.doi.org/10.1590/s0100-204x2002000900014.

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A bioatividade de ácidos húmicos (AH) isolados de lodo da estação de tratamento de esgoto (AHL) e de vermicomposto (AHV) foi avaliada pela ação dessas substâncias sobre o transporte de prótons através da membrana plasmática de células de raízes de café e milho e sua relação com o desenvolvimento dessas espécies. Houve estímulo da área superficial radicular em ambas as espécies cultivadas com ambos AH, mostrando uma concentração ótima em torno de 40 mg L-1. Nessa condição, os tratamentos com AHL e AHV estimularam a H+-ATPase de membrana plasmática em plântulas de café e milho. Os AHL foram mais efetivos na promoção desses efeitos do que os AHV. A modificação do perfil cromatográfico dos AH em solução antes e após o cultivo das plântulas revelou que a interação planta-AH promoveu uma redistribuição das massas moleculares dessas substâncias, sugerindo uma dinâmica de mobilização de subunidades funcionais dos AH por exsudatos das raízes. A análise estrutural dos AH detectou a presença de grupamentos de auxina. A análise comparativa da ação desses dois AH sobre as espécies representantes de plantas monocotiledôneas (milho) e dicotiledôneas (café) apontam para a ativação da H+-ATPase de plasmalema como possível marcador metabólico de bioatividade dos ácidos húmicos.

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Muresan, V., and M. C. Constantinescu. "Distribution of sialoglycoconjugates on the luminal surface of the endothelial cell in the fenestrated capillaries of the pancreas." Journal of Histochemistry & Cytochemistry 33, no. 5 (May 1985): 474–76. http://dx.doi.org/10.1177/33.5.3989274.

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Sialic acid-bearing molecules on the luminal surface of the vascular endothelium in mouse and rat pancreatic capillaries were detected electron microscopically by using a procedure with ferritin hydrazide (FH), after preferential oxidation of sialyl residues with sodium periodate. The distribution of FH on the endothelial surface demonstrated the existence of microdomains with various densities of sialoglycoconjugates oxidizable by sodium periodate and accessible to the tracer. On the plasmalemma proper, FH binding sites were heterogeneously distributed. Their concentration on various microdomains decreased as follows: plasmalemma proper greater than coated pits greater than stomal diaphragms of plasmalemmal vesicles and transendothelial channels, and fenestral diaphragms. The membrane of plasmalemmal vesicles and transendothelial channels was not labeled by FH. Nonspecific binding of FH to the nonoxidized endothelial surface or that oxidized after neuraminidase treatment was relatively low.

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6

Predescu, D., M. Simionescu, N. Simionescu, and G. E. Palade. "Binding and transcytosis of glycoalbumin by the microvascular endothelium of the murine myocardium: evidence that glycoalbumin behaves as a bifunctional ligand." Journal of Cell Biology 107, no. 5 (November 1, 1988): 1729–38. http://dx.doi.org/10.1083/jcb.107.5.1729.

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The binding and transport of glycoalbumin (gA) by the endothelium of murine myocardial microvessels were studied by perfusing in situ 125I-gA or gA-gold complexes (gA-Au) and examining the specimens by radioassays and EM, respectively. After a 3-min perfusion, the uptake of radioiodinated gA is 2.2-fold higher than that of native albumin; it is partially (approximately 55%) competed by either albumin or D-glucose, and almost completely abolished by the concomitant administration of both competitors or by gA. D-mannose and D-galactose are not effective competitors. Unlike albumin-gold complexes that bind restrictively to plasmalemmal vesicles, gA-Au labels the plasma-lemma proper, plasmalemmal vesicles open on the lumen, and most coated pits. Competing albumin prevents gA-Au binding to the membrane of plasmalemmal vesicles, while glucose significantly reduces the ligand binding to plasmalemma proper. Competition with albumin and glucose gives additive effects. Transcytosis of gA-Au, already detected at 3 min, becomes substantial by 30 min. No tracer exit via intercellular junctions was detected. gA-Au progressively accumulates in multivesicular bodies. The results of the binding and competition experiments indicate that the gA behaves as a bifunctional ligand which is recognized by two distinct binding sites: one, located on the plasma membrane, binds as a lectin the glucose residues of gA; whereas the other, confined to plasmalemmal vesicles, recognizes presumably specific domains of the albumin molecule.

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7

Stan, R. V., W. G. Roberts, D. Predescu, K. Ihida, L. Saucan, L. Ghitescu, and G. E. Palade. "Immunoisolation and partial characterization of endothelial plasmalemmal vesicles (caveolae)." Molecular Biology of the Cell 8, no. 4 (April 1997): 595–605. http://dx.doi.org/10.1091/mbc.8.4.595.

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Plasmalemmal vesicles (PVs) or caveolae are plasma membrane invaginations and associated vesicles of regular size and shape found in most mammalian cell types. They are particularly numerous in the continuous endothelium of certain microvascular beds (e.g., heart, lung, and muscles) in which they have been identified as transcytotic vesicular carriers. Their chemistry and function have been extensively studied in the last years by various means, including several attempts to isolate them by cell fractionation from different cell types. The methods so far used rely on nonspecific physical parameters of the caveolae and their membrane (e.g., size-specific gravity and solubility in detergents) which do not rule out contamination from other membrane sources, especially the plasmalemma proper. We report here a different method for the isolation of PVs from plasmalemmal fragments obtained by a silica-coating procedure from the rat lung vasculature. The method includes sonication and flotation of a mixed vesicle fraction, as the first step, followed by specific immunoisolation of PVs on anticaveolin-coated magnetic microspheres, as the second step. The mixed vesicle fraction, is thereby resolved into a bound subfraction (B), which consists primarily of PVs or caveolae, and a nonbound subfraction (NB) enriched in vesicles derived from the plasmalemma proper. The results so far obtained indicate that some specific endothelial membrane proteins (e.g., thrombomodulin, functional thrombin receptor) are distributed about evenly between the B and NB subfractions, whereas others are restricted to the NB subfraction (e.g., angiotensin converting enzyme, podocalyxin). Glycoproteins distribute unevenly between the two subfractions and antigens involved in signal transduction [e.g., annexin II, protein kinase C alpha, the G alpha subunits of heterotrimeric G proteins (alpha s, alpha q, alpha i2, alpha i3), small GTP-binding proteins, endothelial nitric oxide synthase, and nonreceptor protein kinase c-src] are concentrated in the NB (plasmalemma proper-enriched) subfraction rather than in the caveolae of the B subfraction. Additional work should show whether discrepancies between our findings and those already recorded in the literature represent inadequate fractionation techniques or are accounted for by chemical differentiation of caveolae from one cell type to another.

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8

Williams, JB. "Studies on the Epidermis of Temnocephala Vii.* The Basal Region, with Comments on 'Membrane Flow'." Australian Journal of Zoology 33, no. 4 (1985): 413. http://dx.doi.org/10.1071/zo9850413.

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Tubular infoldings of the plasmalemma, and other basal structures in the epidermis of Temnocephala novaezealandiae, are described. At times, the tubular invaginations are greatly elaborated, resulting in a considerably increased plasmalemmal area; also, complex lateral interdigitations occur at the boundaries of the differentiated syncytial epithelia. Many mitochondria are associated with the elaborated membrane. These modifications suggest an enhanced ion transport across the epidermis, and the epidermis is assumed to function in combination with the protonephridial tubules in ionic regulation. Other cytoplasmic structures are correlated with the enhanced plasma membrane, indicating possible pathways of membraneogenesis. Return to the normal epidermal cytomorphology evidently entails a large-scale disassembly of plasma membranes.

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9

Roettger, B. F., R. U. Rentsch, D. Pinon, E. Holicky, E. Hadac, J. M. Larkin, and L. J. Miller. "Dual pathways of internalization of the cholecystokinin receptor." Journal of Cell Biology 128, no. 6 (March 15, 1995): 1029–41. http://dx.doi.org/10.1083/jcb.128.6.1029.

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Receptor molecules play a major role in the desensitization of agonist-stimulated cellular responses. For G protein-coupled receptors, rapid desensitization occurs via receptor phosphorylation, sequestration, and internalization, yet the cellular compartments in which these events occur and their interrelationships are unclear. In this work, we focus on the cholecystokinin (CCK) receptor, which has been well characterized with respect to phosphorylation. We have used novel fluorescent and electron-dense CCK receptor ligands and an antibody to probe receptor localization in a CCK receptor-bearing CHO cell line. In the unstimulated state, receptors were diffusely distributed over the plasmalemma. Agonist occupation stimulated endocytosis via both clathrin-dependent and independent pathways. The former was predominant, leading to endosomal and lysosomal compartments, as well as recycling to the plasmalemma. The clathrin-independent processes led to a smooth vesicular compartment adjacent to the plasmalemma resembling caveolae, which did not transport ligand deeper within the cell. Potassium depletion largely eliminated clathrin-dependent endocytosis, while not interfering with agonist-stimulated receptor movement into subplasmalemmal smooth vesicle compartments. These cellular endocytic events can be related to the established cycle of CCK receptor phosphorylation and dephosphorylation, which we have previously described (Klueppelberg, U. G., L. K. Gates, F. S. Gorelick, and L. J. Miller. 1991. J. Biol. Chem. 266:2403-2408; Lutz, M. P., D. I. Pinon, L. K. Gates, S. Shenolikar, and L. J. Miller. 1993. J. Biol. Chem. 268:12136-12142). The rapid onset and peak of receptor phosphorylation after agonist occupation correlates best with a plasmalemmal localization, while stimulated receptor phosphatase activity correlates best with receptor residence in intracellular compartments. We postulate that the smooth vesicular compartment adjacent to the plasmalemma functions for the rapid resensitization of the receptor, while the classical clathrin-mediated endocytotic pathway is key for receptor downregulation via lysosomal degradation, as well as less rapid resensitization.

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10

Simionescu, M., N. Simionescu, F. Santoro, and G. E. Palade. "Differentiated microdomains of the luminal plasmalemma of murine muscle capillaries: segmental variations in young and old animals." Journal of Cell Biology 100, no. 5 (May 1, 1985): 1396–407. http://dx.doi.org/10.1083/jcb.100.5.1396.

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We investigated the luminal surface of the continuous endothelium of the microvasculature of the murine heart and diaphragm to find out whether it has differentiated microdomains. The probes were ferritin molecules, cationized to pI's 6.8, 7.15, 7.6, 8.0 and 8.4, which were introduced by retrograde or anterograde perfusion through the aorta or vena cava after the blood was removed from the vasculature. The pattern of labeling was analyzed by electron microscopy and assessed quantitatively by morphometry in arterioles, capillaries, and venules identified in bipolar microvascular fields in the diaphragm. The results showed that the plasmalemma proper was heavily but discontinuously labeled by all cationized ferritins (CF) used, the labeling being less extensive on the venular endothelium. CF had access as individual molecules to a fraction of the vesicular population opened on the luminal front of the endothelium. Plasmalemmal vesicle labeling increased from approximately 10 to approximately 25% as the pI decreased from 8.4 to 6.8. Vesicle labeling also increased with CF concentration in the perfusate. All CF binding sites were removed by pronase and papain. Heparinase and heparitinase caused only a slight reduction in CF labeling. Neuraminidase decreased the extent and density of labeling, especially on the plasmalemma proper of the venular endothelium; this decrease was particularly pronounced in old animals.

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11

Ghinea, N., and N. Simionescu. "Anionized and cationized hemeundecapeptides as probes for cell surface charge and permeability studies: differentiated labeling of endothelial plasmalemmal vesicles." Journal of Cell Biology 100, no. 2 (February 1, 1985): 606–12. http://dx.doi.org/10.1083/jcb.100.2.606.

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To obtain small membrane markers easily accessible to the charged groups of the cell surface, we prepared, from hemeundecapeptide (HUP), three derivatives that maintain the peroxidatic activity: the anionized hemeundecapeptide, Mr 1,963, estimated diameter 1.68 nm, pl 3.5, for the detection of basic groups; and both a cationized hemeundecapeptide containing predominantly tertiary amino groups, Mr 2,215, estimated diameter 1.75 nm, pl 9.0, and a cationized hemeundecapeptide containing only primary amino groups, Mr 2,271, estimated diameter 1.75 nm, pl 10.6, for labeling acidic residues. The markers were perfused in situ in mice to label the luminal surface of fenestrated endothelium of pancreatic capillaries. Specimens were processed through the cytochemical reaction for peroxidatic activity and examined by electron microscopy. The anionized HUP and HUP (pl 4.85) marked the plasmalemma proper, the coated pits, and the membrane and diaphragms of plasmalemmal vesicles and transendothelial channels. The cationized HUP containing predominantly tertiary amino groups (pl 9.0) decorated all cell surface components with the exception of plasmalemmal vesicles and channels; the latter were, however, labeled by the cationized HUP containing only primary groups (pl 10.6), which suggests that these structures contain on their luminal surface very weak acidic residues of high pKa values. The fact that the membrane of plasmalemmal vesicles can discriminate against permeant cationic macromolecules only up to a pl of approximately 9.0 indicates that in the electrostatic restriction there is a charge limit. In the case of fenestrated capillary endothelium, the upper charge limit seems to be a pl of approximately 9.0. In these vessels, the charge discrimination is effective for molecules as small as 2 nm.

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12

Tsunoda, Yasuhiro. "Ca2+ currents and acid secretion in the isolated parietal cell involved in response to gastrin, compound 48/80, and ethylenediamine tetraacetic acid." Biochemistry and Cell Biology 65, no. 2 (February 1, 1987): 144–62. http://dx.doi.org/10.1139/o87-020.

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In intact guinea pig parietal cells, gastrin or compound 48/80 caused an initial increase in cytosolic Ca2+ concentration and subsequent acid secretion, owing to release of intracellulary stored Ca2+ besides the Ca2+ entry from the extracellular space. However, the maximum gastrin-induced Ca2+ entry into the cell was delayed by 60 min, a time which coincided with sustained acid secretion (by gastrin) that was dependent on medium Ca2+. On the other hand, there are two ATP-dependent Ca2+-removal systems detected in either plasmalemma or smooth surfaced membrane besides that of mitochondria. The plasmalemmal Ca2+-removal system was dependent on calmodulin. Smooth surfaced membrane vesicles caused an ATP-dependent Ca2+ uptake that was almost similar to that taken by saponin-permiabilized cell. In this system (permeable cell), myo-inositol 1,4,5-triphosphate (InsP3) caused the release of ATP-accumulated Ca2+ into the cytosol, suggesting an ATP-dependent and InsP3-sensitive Ca2+ pool(s) is in or near the smooth surfaced membranes. The ATP-dependent Ca2+ uptake by vesicles was markedly enhanced by the stimulation of cells with gastrin, compound 48/80, or EDTA. The increase of this Ca2+ uptake in stimulated cells by plasmalemmal vesicles exceeded that by smooth surfaced ones. The increase of the Ca2+ uptake by plasmalemmal vesicles was abolished by the cease of intracellular Ca2+ release without Ca2+ entry. In addition, gastrin or compound 48/80 evoked an early Ca2+ efflux across the plasma membrane owing to a pump that was independent of medium Ca2+ in intact cells. These results suggest that in the first acid secretion by gastrin or others, the Ca2+ released, which may be derived from an ATP-dependent and InsP3-sensitive Ca2+ pool, is mainly pumped out by the plasmalemmal Ca2+-removal system rather than the intracellular Ca2+-removal system; whereas the sustained acid secretion by gastrin required medium Ca2+ and in this phase, Ca2+ efflux across the plasma membrane became lower, suggesting that an ATP-dependent Ca2+ pool may be replenished by Ca2+ entering from the extracellular space.

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13

Bajno, Lydia, Xiao-Rong Peng, Alan D. Schreiber, Hsiao-Ping Moore, William S. Trimble, and Sergio Grinstein. "Focal Exocytosis of Vamp3-Containing Vesicles at Sites of Phagosome Formation." Journal of Cell Biology 149, no. 3 (May 1, 2000): 697–706. http://dx.doi.org/10.1083/jcb.149.3.697.

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Phagocytosis involves the receptor-mediated extension of plasmalemmal protrusions, called pseudopods, which fuse at their tip to engulf a particle. Actin polymerizes under the nascent phagosome and may propel the protrusion of pseudopods. Alternatively, membrane extension could result from the localized insertion of intracellular membranes into the plasmalemma next to the particle. Here we show focal accumulation of VAMP3-containing vesicles, likely derived from recycling endosomes, in the vicinity of the nascent phagosome. Using green fluorescent protein (GFP) as both a fluorescent indicator and an exofacial epitope tag, we show that polarized fusion of VAMP3 vesicles precedes phagosome sealing. It is therefore likely that targeted delivery of endomembranes contributes to the elongation of pseudopods. In addition to mediating pseudopod formation, receptor-triggered focal secretion of endosomes may contribute to polarized membrane extension in processes such as lamellipodial elongation or chemotaxis.

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Schilling, William P., William G. Sinkins, and Mark Estacion. "Maitotoxin activates a nonselective cation channel and a P2Z/P2X7-like cytolytic pore in human skin fibroblasts." American Journal of Physiology-Cell Physiology 277, no. 4 (October 1, 1999): C755—C765. http://dx.doi.org/10.1152/ajpcell.1999.277.4.c755.

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Maitotoxin (MTX), a potent cytolytic agent, activates Ca2+ entry via nonselective cation channels in virtually all types of cells. The identity of the channels involved and the biochemical events leading to cell lysis remain unknown. In the present study, the effect of MTX on plasmalemmal permeability of human skin fibroblasts was examined. MTX produced a time- and concentration-dependent increase in cytosolic free Ca2+ concentration that depended on extracellular Ca2+ and was relatively insensitive to blockade by extracellular lanthanides. MTX also produced a time- and concentration-dependent increase in plasmalemma permeability to larger molecules as indicated by 1) uptake of ethidium (314 Da), 2) uptake of YO-PRO-1 (375 Da), 3) release of intracellular fura 2 (636 Da), 4) uptake of POPO-3 (715 Da), and, ultimately, 5) release of lactate dehydrogenase (relative molecular weight of 140,000). At the single cell level, uptake of YO-PRO-1 correlated in time with the appearance of large MTX-induced membrane currents carried by the organic cation, N-methyl-d-glucamine (167 Da). Thus MTX initially activates Ca2+-permeable cation channels and later induces the formation of large pores. These effects of MTX on plasmalemmal permeability are similar to those seen on activation of P2Z/P2X7 receptors in a variety of cell types, raising the intriguing possibility that MTX and P2Z/P2X7 receptor stimulation activate a common cytolytic pore.

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15

Fairn, Gregory D., Koji Ogata, Roberto J. Botelho, Philip D. Stahl, Richard A. Anderson, Pietro De Camilli, Tobias Meyer, Shoshana Wodak, and Sergio Grinstein. "An electrostatic switch displaces phosphatidylinositol phosphate kinases from the membrane during phagocytosis." Journal of Cell Biology 187, no. 5 (November 30, 2009): 701–14. http://dx.doi.org/10.1083/jcb.200909025.

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Plasmalemmal phosphatidylinositol (PI) 4,5-bisphosphate (PI4,5P2) synthesized by PI 4-phosphate (PI4P) 5-kinase (PIP5K) is key to the polymerization of actin that drives chemotaxis and phagocytosis. We investigated the means whereby PIP5K is targeted to the membrane and its fate during phagosome formation. Homology modeling revealed that all PIP5K isoforms feature a positively charged face. Together with the substrate-binding loop, this polycationic surface is proposed to constitute a coincidence detector that targets PIP5Ks to the plasmalemma. Accordingly, manipulation of the surface charge displaced PIP5Ks from the plasma membrane. During particle engulfment, PIP5Ks detached from forming phagosomes as the surface charge at these sites decreased. Precluding the change in surface charge caused the PIP5Ks to remain associated with the phagosomal cup. Chemically induced retention of PIP5K-γ prevented the disappearance of PI4,5P2 and aborted phagosome formation. We conclude that a bistable electrostatic switch mechanism regulates the association/dissociation of PIP5Ks from the membrane during phagocytosis and likely other processes.

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Doyle, D. D., D. M. Brill, J. A. Wasserstrom, T. Karrison, and E. Page. "Saxitoxin binding and "fast" sodium channel inhibition in sheep heart plasma membrane." American Journal of Physiology-Heart and Circulatory Physiology 249, no. 2 (August 1, 1985): H328—H336. http://dx.doi.org/10.1152/ajpheart.1985.249.2.h328.

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We compared specific [3H]saxitoxin (STX) binding to isolated sheep ventricular sarcolemmal vesicles with inhibition of maximal action potential upstroke velocity (V max) by STX and tetrodotoxin (TTX) in sheep trabeculae carneae. In sarcolemmal vesicles purified 30 to 40 times over cardiac homogenate, STX binding at 0 degrees C in Na-free solution exhibited both high-affinity sites (KD = 0.22 +/- 0.05 nM, n = 85 +/- 13 fmol/mg protein) and low-affinity sites (KD = 11 +/- 4 nM, n = 360 +/- 42). The STX-inhibition constant for V max in Tyrode solution at 37 degrees C was 280 nM. TTX was approximately 10% as effective as STX in displacing bound [3H]STX and inhibiting V max. Allowing for different experimental conditions during [3H]STX binding and V max measurements, we suggest that the low-affinity sites are physiologically relevant "fast" Na+ channels of myocardial cells. Combining morphometric data for plasmalemmal area of mammalian cardiac myocytes with n for low-affinity sites, we estimate 3.6-7.6 fast Na+ channels/micron2 plasmalemma.

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Stow, J. L., L. Kjéllen, E. Unger, M. Höök, and M. G. Farquhar. "Heparan sulfate proteoglycans are concentrated on the sinusoidal plasmalemmal domain and in intracellular organelles of hepatocytes." Journal of Cell Biology 100, no. 3 (March 1, 1985): 975–80. http://dx.doi.org/10.1083/jcb.100.3.975.

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The distribution of cell surface heparan sulfate proteoglycans (HSPGs) was determined in rat liver by immunocytochemistry. A polyclonal antibody was raised against HSPGs purified from rat liver microsomes which specifically immunoprecipitated liver membrane HSPGs. It was shown to recognize both the heparin-releasable and membrane-intercalated form of membrane HSPGs and to recognize determinants on the core protein of these HSPGs. By immunocytochemistry membrane HSPGs were localized to hepatocytes. The distribution of HSPGs at the cell surface of the hepatocyte was restricted to the sinusoidal domain of the plasmalemma; there was little or no staining of the lateral or bile canalicular domains. Intracellularly, HSPGs were occasionally detected in cisternae of the rough endoplasmic reticulum and were regularly found in Golgi cisternae--usually distributed across the entire Golgi stack. HSPGs were also localized in some endosomes, lysosomes, and cytoplasmic vesicles of hepatocytes. We conclude that the HSPGs recognized by this antibody have a restricted distribution in rat liver: they are largely confined to the sinusoidal plasmalemmal domain and to biosynthetic and endocytic compartments of hepatocytes.

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SHIMOMURA, Shoji, and Shinichiro WATANABE. "Auxin receptors in plasmalemma." membrane 18, no. 1 (1993): 34–42. http://dx.doi.org/10.5360/membrane.18.34.

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19

Sztul, E. S., K. E. Howell, and G. E. Palade. "Biogenesis of the polymeric IgA receptor in rat hepatocytes. II. Localization of its intracellular forms by cell fractionation studies." Journal of Cell Biology 100, no. 4 (April 1, 1985): 1255–61. http://dx.doi.org/10.1083/jcb.100.4.1255.

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In the companion paper (Sztul, E. S., K. E. Howell, and G. E. Palade, J. Cell Biol., 100:1248-1254), we have shown that pulse labeling of hepatic proteins with [35S]cysteine can be obtained in vivo in intact rats. Soluble label clears the plasma in approximately 5 min, and incorporated label reaches peak values in the liver approximately 20 min after injection. In the present study, we show that the 105,000-mol-wt protein (105K), kinetically the earliest intracellular form of secretory component (SC), is the predominant form found, between 5 and 20 min postinjection, in homogeneous rough microsomal fractions. The second kinetically defined form, i.e., 116K, is the predominant species present in relatively homogeneous, light Golgi fractions in which it appears at approximately 15 min, and peaks at approximately 25 min, postinjection. The third kinetically defined form, 120K, is found 30 min after injection as the major SC species (albeit still accompanied by its immediate precursor, 116K), in a sinusoidal plasmalemmal fraction isolated by immunoadsorption to anti-SC-coated Sepharose beads. These findings lead to the following conclusions: (a) SC is synthesized on polysomes attached to the rough endoplasmic reticulum (ER) membrane; (b) it is partially translocated across the ER membrane and core glycosylated co-translationally to give a 105K peptide; (c) 105K moves from the ER to the Golgi complex where it is terminally glycosylated to give the 116K form; (d) the latter moves to the sinusoidal plasmalemma where it appears together with the final mature form, 120K. Kinetic evidence indicates that the vesicular carriers involved in the transport of SC from the Golgi complex to the sinusoidal plasmalemma, and from the latter to the biliary front of the hepatocytes, are present in a Golgi heavy fraction and a crude carrier vesicle fraction from which they remain to be isolated, purified, and characterized.

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20

Etxeberria, Ed, and Pedro Gonzalez. "Simultaneous Isolation of Tonoplast and Plasmalemma from Citrus Juice Cells: Combination of Sucrose Gradient and Two Phase Partitioning." HortScience 39, no. 1 (February 2004): 174–76. http://dx.doi.org/10.21273/hortsci.39.1.174.

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By combining the principles of density gradient separation and two phase partitioning, we devised a system to obtain highly pure plasmalemma and tonoplast vesicles from citrus (Citrus limettioides Tan.) juice cells. Both tonoplast and plasmalemma fractions were virtually free from golgi, endoplasmic reticulum and mitochondria contamination. Plasmalemma and tonoplast samples were also clean from each other cross-contaminants. Immediately after isolation, 72% of the plasmalemma and 82% of the tonoplast vesicles were oriented rightside-out according to enzyme marker activities. After freezing and thawing, however, plasmalemma vesicles re-oriented evenly but orientation of tonoplast vesicles remained unchanged. Differential changes in marker activities before and after freezing and thawing indicated that the low levels of plasmalemma contamination within the tonoplast fractions were due to the presence of a separate population of plasmalemma vesicles and not to the existence of hybrid vesicles. The method described in this communication allows for future studies on photoassimilate accumulation in cells of important horticultural storage organs.

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Wisnoskey, Brian J., Mark Estacion, and William P. Schilling. "Maitotoxin-induced cell death cascade in bovine aortic endothelial cells: divalent cation specificity and selectivity." American Journal of Physiology-Cell Physiology 287, no. 2 (August 2004): C345—C356. http://dx.doi.org/10.1152/ajpcell.00473.2003.

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The maitotoxin (MTX)-induced cell death cascade in bovine aortic endothelial cells (BAECs), a model for Ca2+ overload-induced toxicity, reflects three sequential changes in plasmalemmal permeability. MTX initially activates Ca2+-permeable, nonselective cation channels (CaNSC) and causes a massive increase in cytosolic free Ca2+ concentration ([Ca2+]i). This is followed by the opening of large endogenous cytolytic/oncotic pores (COP) that allow molecules <800 Da to enter the cell. The cells then lyse not by rupture of the plasmalemma but through the activation of a “death” channel that lets large proteins (e.g., 140–160 kDa) leave the cell. These changes in permeability are accompanied by the formation of membrane blebs. In this study, we took advantage of the well-known differences in affinity of various Ca2+-binding proteins for Ca2+ and Sr2+ vs. Ba2+ to probe their involvement in each phase of the cell death cascade. Using fluorescence techniques at the cell population level (cuvette-based) and at the single-cell level (time-lapse videomicroscopy), we found that the replacement of Ca2+ with either Sr2+ or Ba2+ delayed both MTX-induced activation of COP, as indicated by the uptake of ethidium bromide, and subsequent cell lysis, as indicated by the uptake of propidium iodide or the release of cell-associated green fluorescent protein. MTX-induced responses were mimicked by ionomycin and were significantly delayed in BAPTA-loaded cells. Experiments at the single-cell level revealed that Ba2+ not only delayed the time to cell lysis but also caused desynchronization of the lytic phase. Last, membrane blebs, which were numerous and spherical in Ca2+-containing solutions, were poorly defined and greatly reduced in number in the presence of Ba2+. Taken together, these results suggest that intracellular high-affinity Ca2+-binding proteins are involved in the MTX-induced changes in plasmalemmal permeability that are responsible for cell demise.

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22

Sommer, J. R., T. High, P. Ingram, D. Kopf, R. Nassar, and I. Taylor. "Avian Extended Junctional SR: 3-D Geometry Rendered in Stereo." Microscopy and Microanalysis 3, S2 (August 1997): 247–48. http://dx.doi.org/10.1017/s1431927600008126.

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Extended junctional sarcoplasmic reticulum (EJSR) is an invariant differentiation of the sarcoplasmic reticulum (SR) in bird cardiac myocytes (CM) and central to excitation-contraction coupling (ECC). EJSR occurs as both continuous and discontinuous extensions of junctional sarcoplasmic reticulum (JSR), and surrounds and pervades the Z/I band as the “ EJSR Z-rete” whose geometry has mechanistic implications for the function of “couplings” in ECC, in general. “Peripheral coupling(s)” (PC) in birds, and the additional “interior coupling(s)” (IC) at transverse tubules (TT) in mammals, are formed by tight apposition to plasmalemma of JSR, a specialized calcium (Ca) store of the SR. Free SR (FSR; i.e. free of JSR/EJSR specializations) is the rest of the smooth, tubular SR network, which connects intercalated patches of EJSR forming the EJSR Z-retes and, elsewhere, displays both longitudinal and transverse geometries in surrounding the contractile material for the purpose of sequestering Ca after each muscle contraction. Except for EJSR having no plasmalemmal contact, morphologically, EJSR and JSR are homologues:1 both have similar sizes; are studded (approx. 32 nm center-to-center) with junctional processes (JP; ryanodine receptor (RyR)/-Ca-release channels);

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23

Corbett-Nelson, Elaine F., David Mason, John G. Marshall, Yves Collette, and Sergio Grinstein. "Signaling-dependent immobilization of acylated proteins in the inner monolayer of the plasma membrane." Journal of Cell Biology 174, no. 2 (July 10, 2006): 255–65. http://dx.doi.org/10.1083/jcb.200605044.

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Phospholipids play a critical role in the recruitment and activation of several adaptors and effectors during phagocytosis. Changes in lipid metabolism during phagocytosis are restricted to the phagocytic cup, the area of the plasmalemma lining the target particle. It is unclear how specific lipids and lipid-associated molecules are prevented from diffusing away from the cup during the course of phagocytosis, a process that often requires several minutes. We studied the mobility of lipid-associated proteins at the phagocytic cup by measuring fluorescence recovery after photobleaching. Lipid-anchored (diacylated) fluorescent proteins were freely mobile in the unstimulated membrane, but their mobility was severely restricted at sites of phagocytosis. Only probes anchored to the inner monolayer displayed reduced mobility, whereas those attached to the outer monolayer were unaffected. The immobilization persisted after depletion of plasmalemmal cholesterol, ruling out a role of conventional “rafts.” Corralling of the probes by the actin cytoskeleton was similarly discounted. Instead, the change in mobility required activation of tyrosine kinases. We suggest that signaling-dependent recruitment of adaptors and effectors with lipid binding domains generates an annulus of lipids with restricted mobility.

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24

Touret, Nicolas, Natalia Martin-Orozco, Paul Paroutis, Wendy Furuya, Steven Lam-Yuk-Tseung, John Forbes, Philippe Gros, and Sergio Grinstein. "Molecular and cellular mechanisms underlying iron transport deficiency in microcytic anemia." Blood 104, no. 5 (September 1, 2004): 1526–33. http://dx.doi.org/10.1182/blood-2004-02-0731.

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Abstract A mutation of the iron transporter Nramp2 (DMT1, Slc11a2) causes microcytic anemia in mk mice and in Belgrade rats by impairing iron absorption in the duodenum and in erythroid cells, causing severe iron deficiency. Both mk and Belgrade animals display a glycine-to-arginine substitution at position 185 (G185R) in the fourth predicted transmembrane domain of Nramp2. To study the molecular basis for the loss of function of Nramp2G185R, we established cell lines stably expressing extracellularly tagged versions of wild-type (WT) or mutated transporters. Like WT Nramp2, the G185R mutant was able to reach the plasmalemma and endosomal compartments, but with reduced efficiency. Instead, a large fraction of Nramp2G185R was detected in the endoplasmic reticulum, where it was unstable and was rapidly degraded by a proteasome-dependent mechanism. Moreover, the stability of the mutant protein that reached the plasma membrane was greatly reduced, further diminishing its surface density at steady state. Last, the specific metal transport activity of plasmalemmal Nramp2G185R was found to be significantly depressed, compared with its WT counterpart. Thus, a singlepoint mutation results in multiple biosynthetic and functional defects that combine to produce the impaired iron deficiency that results in microcytic anemia.

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25

Boronikhina, T. V., T. A. Lomanovskaya, and A. N. Yatskovskii. "Erythrocyte Plasmalemma and Its Changes During the Cell Lifespan." Journal of Anatomy and Histopathology 10, no. 2 (July 15, 2021): 62–72. http://dx.doi.org/10.18499/2225-7357-2021-10-2-62-72.

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The article reviews literature on the organization of the erythrocyte plasmalemma and its rearrangements at different periods of the cell lifespan. In the absence of a nucleus and organelles, the plasmalemma is the only structural element of erythrocytes involved in all processes of their vital activity. The plasmalemma supports the disk-like shape of the erythrocyte, provides its ability to reversible deformation, maintains intracellular homeostasis, participates in gas transport and energy metabolism, also transfers hormones, enzymes, antibodies, medicines and other substances on its surface. The polyfunctionality of the plasmalemma is provided by the peculiarities of its lipid, protein, and carbohydrate composition, as well as by the presence of a unique cytoskeleto n, morphologically associated with the erythrocyte membrane. The plasmalemma has the substantial modifications during the erythrocyte lifespan, namely, in maturation of reticulocytes, in the processes of functioning, aging, and cell death. Biochemical rearrangements of the plasmalemma serve as triggers for events such as membrane vesiculation, eryptosis, and elimination of senescent erythrocytes by macrophages. Age-related changes in the erythrocyte plasmalemma are adoptive in nature and aimed at maintaining cellular homeostasis and functional activity of these formed elements during a four-month stay in the bloodstream.

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26

RABJEAU, A., F. FOUSSARD, G. MAURAS, and J. F. DUBREMETZ. "Enrichment and biochemical characterization of Toxoplasma gondii tachyzoite plasmalemma." Parasitology 114, no. 5 (May 1997): 421–26. http://dx.doi.org/10.1017/s0031182096008670.

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The protozoan parasite Toxoplasma gondii possesses a triple surface membrane called the pellicle. This is made of an outer plasmalemma and an inner membrane complex lying under the plasmalemma. Using a high salt glycerol treatment followed by sonication, we have obtained a partial dissociation of the pellicle. A plasmalemma-enriched fraction was isolated on 0·7M sucrose. It was identified by immunodetection of the tachyzoite major surface antigens. Protein content, resolved by SDS–PAGE, revealed that the surface protein SAG1 is the major component of the plasmalemma. The plasmalemma fraction is made of small vesicles (20–100 nm) which possess a low density (1·085–1·090 g/cm3 in sucrose) contrasting with other eukaryotic plasma membranes (1·12–1·16 g/cm3).

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27

Crane, F. L., and I. M. Møller. "PLASMALEMMA REDOX FUNCTIONS IN PLANTS." Physiologia Plantarum 73, no. 1 (May 1988): 159–60. http://dx.doi.org/10.1111/j.1399-3054.1988.tb09209.x.

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28

Goyer, Claudia, Pierre-Mathieu Charest, Vicky Toussaint, and Carole Beaulieu. "Ultrastructural effects of thaxtomin A produced by Streptomyces scabies on mature potato tuber tissues." Canadian Journal of Botany 78, no. 3 (April 20, 2000): 374–80. http://dx.doi.org/10.1139/b00-013.

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The cytological and ultrastructural modifications induced by thaxtomin A, a phytotoxin produced by Streptomyces scabies, were analyzed on mature field-grown potato tuber tissues. In tissue sampled during the first 12 h after treatment with thaxtomin A, the plasmalemma of parenchyma cells was detached from the cell wall in several places. However, the plasmalemma did not appear ruptured. The intercellular spaces between the retracted plasmalemma and the cell wall often contained fibrillar material. After a longer period of time, cells from tissues treated with thaxtomin A showed significant disorganization, such as detachment and invagination of the plasmalemma, the presence of a fibrillar-like material in the cytoplasm, and electron-dense material associated with moribund cellular features.Key words: common scab, potato, phytotoxin, Solanum tuberosum.

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29

Weber, Angela, Elke Fischer, Helmut Schipp von Branitz, and Ulrich Lüttge. "The Effects of the Herbicide Sethoxydim on Transport Processes in Sensitive and Tolerant Grass Species I. Effects on the Electrical Membrane Potential and Alanine Uptake." Zeitschrift für Naturforschung C 43, no. 3-4 (April 1, 1988): 249–56. http://dx.doi.org/10.1515/znc-1988-3-416.

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Sethoxydim is a postemergence herbicide used to control grass weeds. Application at concentrations higher than 0.1 mᴍ to leaf segments of the sensitive grass species Poa pratensis and Festuca ovina and the tolerant species Poa annua and Festuca rubra, caused a reduction of the electrical membrane potential (⊿E). The depolarization was reversible and depended linearly on the herbicide concentration. The passive diffusion component of ⊿E was not affected by sethoxydim indicating that the herbicide did not change passive permeability characteristics of the plasmalemma. Consequently sethoxydim reduced the active component of ⊿E that depended on primary active transport processes across the plasmalemma. Moreover, sethoxydim increased the reduction of ⊿E of grass leaf cells that was associated with the onset of H+-amino acid cotransport. Simultaneously the uptake of alanine into leaf segments was reduced. From these results it had to be concluded that the plasmalemma-bound H+-ATPase was inhibited by sethoxydim in sensitive and tolerant grasses. In vitro ATP hydrolysis of plasmalemma vesicles isolated from grass leaves by polymer phase partitioning, however, was not inhibited by sethoxydim. Apparently another primary active transport mechanism that may contribute to an electrochemical H+- gradient across the plasmalemma, i.e. a plasmalemma-bound redox system, should be the site of inhibition responsible for the membrane effects of sethoxydim observed in vivo.

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30

Pastore, Mayra B., Rosalina Villalon Landeros, Dong-bao Chen, and Ronald R. Magness. "Structural analysis of estrogen receptors: interaction between estrogen receptors and cav-1 within the caveolae†." Biology of Reproduction 100, no. 2 (August 23, 2018): 495–504. http://dx.doi.org/10.1093/biolre/ioy188.

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Abstract Pregnancy is a physiologic state of substantially elevated estrogen biosynthesis that maintains vasodilator production by uterine artery endothelial cells (P-UAECs) and thus uterine perfusion. Estrogen receptors (ER-α and ER-β; ESR1 and ESR2) stimulate nongenomic rapid vasodilatory responses partly through activation of endothelial nitric oxide synthase (eNOS). Rapid estrogenic responses are initiated by the ∼4% ESRs localized to the plasmalemma of endothelial cells. Caveolin-1 (Cav-1) interactions within the caveolae are theorized to influence estrogenic effects mediated by both ESRs. Hypothesis: Both ESR1 and ESR2 display similar spatial partitioning between the plasmalemma and nucleus of UAECs and have similar interactions with Cav-1 at the plasmalemma. Using transmission electron microscopy, we observed numerous caveolae structures in UAECs, while immunogold labeling and subcellular fractionations identified ESR1 and ESR2 in three subcellular locations: membrane, cytosol, and nucleus. Bioinformatics approaches to analyze ESR1 and ESR2 transmembrane domains identified no regions that facilitate ESR interaction with plasmalemma. However, sucrose density centrifugation and Cav-1 immunoisolation columns uniquely demonstrated very high protein–protein association only between ESR1, but not ESR2, with Cav-1. These data demonstrate (1) both ESRs localize to the plasmalemma, cytosol and nucleus; (2) neither ESR1 nor ESR2 contain a classic region that crosses the plasmalemma to facilitate attachment; and (3) ESR1, but not ESR2, can be detected in the caveolar subcellular domain demonstrating ESR1 is the only ESR bound in close proximity to Cav-1 and eNOS within this microdomain. Lack of protein–protein interaction between Cav-1 and ESR2 demonstrates a novel independent association of these proteins at the plasmalemma.

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31

Bentrup, Friedrich-Wilhelm. "Potassium ion channels in the plasmalemma." Physiologia Plantarum 79, no. 4 (August 1990): 705–11. http://dx.doi.org/10.1034/j.1399-3054.1990.790420.x.

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32

Trockner, Verena, and Erasmo Marrè. "Plasmalemma Redox Chain and H+ Extrusion." Plant Physiology 87, no. 1 (May 1, 1988): 30–35. http://dx.doi.org/10.1104/pp.87.1.30.

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33

Thinnes, Friedrich P. "Modulator of plasmalemma standing VDAC revealed !?" Molecular Genetics and Metabolism 91, no. 1 (May 2007): 116–18. http://dx.doi.org/10.1016/j.ymgme.2007.01.006.

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34

HANSEN, ULF-PETER, JöRG KOLBOWSKI, and HOLGER DAU. "Relationship between Photosynthesis and Plasmalemma Transport." Journal of Experimental Botany 38, no. 12 (1987): 1965–81. http://dx.doi.org/10.1093/jxb/38.12.1965.

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35

Harris, N., and N. J. Chaffey. "Plasmatubules - real modifications of the plasmalemma." Nordic Journal of Botany 6, no. 5 (June 28, 2008): 599–607. http://dx.doi.org/10.1111/j.1756-1051.1986.tb00460.x.

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36

Marrè, Maria Teresa, Anna Moroni, Francesco G. Albergoni, and Erasmo Marrè. "Plasmalemma Redox Activity and H+ Extrusion." Plant Physiology 87, no. 1 (May 1, 1988): 25–29. http://dx.doi.org/10.1104/pp.87.1.25.

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37

Matoušková, J., L. Nešpůrková, R. Rybová, and K. Janáček. "Redox activity ofHydrodictyon reticulatum plasmalemma vesicles." Folia Microbiologica 44, no. 4 (August 1999): 419–24. http://dx.doi.org/10.1007/bf02903716.

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38

Bentrup, Friedrich-Wilhelm. "Potassium ion channels in the plasmalemma." Physiologia Plantarum 79, no. 4 (August 1990): 705–11. http://dx.doi.org/10.1111/j.1399-3054.1990.tb00048.x.

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39

Orshal, Julia M., and Raouf A. Khalil. "Gender, sex hormones, and vascular tone." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 286, no. 2 (February 2004): R233—R249. http://dx.doi.org/10.1152/ajpregu.00338.2003.

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The greater incidence of hypertension and coronary artery disease in men and postmenopausal women compared with premenopausal women has been related, in part, to gender differences in vascular tone and possible vascular protective effects of the female sex hormones estrogen and progesterone. However, vascular effects of the male sex hormone testosterone have also been suggested. Estrogen, progesterone, and testosterone receptors have been identified in blood vessels of human and other mammals and have been localized in the plasmalemma, cytosol, and nuclear compartments of various vascular cells, including the endothelium and the smooth muscle. The interaction of sex hormones with cytosolic/nuclear receptors triggers long-term genomic effects that could stimulate endothelial cell growth while inhibiting smooth muscle proliferation. Activation of plasmalemmal sex hormone receptors may trigger acute nongenomic responses that could stimulate endothelium-dependent mechanisms of vascular relaxation such as the nitric oxide-cGMP, prostacyclin-cAMP, and hyperpolarization pathways. Additional endothelium-independent effects of sex hormones may involve inhibition of the signaling mechanisms of vascular smooth muscle contraction such as intracellular Ca2+ concentration and protein kinase C. The sex hormone-induced stimulation of the endothelium-dependent mechanisms of vascular relaxation and inhibition of the mechanisms of vascular smooth muscle contraction may contribute to the gender differences in vascular tone and may represent potential beneficial vascular effects of hormone replacement therapy during natural and surgically induced deficiencies of gonadal hormones.

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40

Laux, Thorsten, Kiyoko Fukami, Marcus Thelen, Tamara Golub, Dunja Frey, and Pico Caroni. "Gap43, Marcks, and Cap23 Modulate Pi(4,5)p2 at Plasmalemmal Rafts, and Regulate Cell Cortex Actin Dynamics through a Common Mechanism." Journal of Cell Biology 149, no. 7 (June 26, 2000): 1455–72. http://dx.doi.org/10.1083/jcb.149.7.1455.

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The dynamic properties of the cell cortex and its actin cytoskeleton determine important aspects of cell behavior and are a major target of cell regulation. GAP43, myristoylated alanine-rich C kinase substrate (MARCKS), and CAP23 (GMC) are locally abundant, plasmalemma-associated PKC substrates that affect actin cytoskeleton. Their expression correlates with morphogenic processes and cell motility, but their role in cortex regulation has been difficult to define mechanistically. We now show that the three proteins accumulate at rafts, where they codistribute with PI(4,5)P2, and promote its retention and clustering. Binding and modulation of PI(4,5)P2 depended on the basic effector domain (ED) of these proteins, and constructs lacking the ED functioned as dominant inhibitors of plasmalemmal PI(4,5)P2 modulation. In the neuronlike cell line, PC12, NGF- and substrate-induced peripheral actin structures, and neurite outgrowth were greatly augmented by any of the three proteins, and suppressed by ΔED mutants. Agents that globally mask PI(4,5)P2 mimicked the effects of GMC on peripheral actin recruitment and cell spreading, but interfered with polarization and process formation. Dominant negative GAP43(ΔED) also interfered with peripheral nerve regeneration, stimulus-induced nerve sprouting and control of anatomical plasticity at the neuromuscular junction of transgenic mice. These results suggest that GMC are functionally and mechanistically related PI(4,5)P2 modulating proteins, upstream of actin and cell cortex dynamics regulation.

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41

Woods, J. W., M. Doriaux, and M. G. Farquhar. "Transferrin receptors recycle to cis and middle as well as trans Golgi cisternae in Ig-secreting myeloma cells." Journal of Cell Biology 103, no. 1 (July 1, 1986): 277–86. http://dx.doi.org/10.1083/jcb.103.1.277.

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The recycling itinerary of plasma membrane transferrin receptors (TFR) was charted in IgG-secreting mouse myeloma cells (RPC 5.4) by tagging surface receptors with either bound anti-transferrin receptor antibodies (anti-TFR) or Fab fragments thereof and determining the intracellular destinations of the tagged receptors by immunocytochemistry. By immunofluorescence, TFR tagged with either probe were seen to be rapidly internalized and translocated from the cell surface to the juxtanuclear (Golgi) region. When localized by immunoperoxidase procedures at the electron microscopic level, the anti-TFR-labeled receptors were detected in all cisternae (cis, middle, and trans) of the Golgi stacks as well as in endosomes and trans Golgi reticular elements. There was no difference in the routing of TFR tagged with monovalent Fab and those tagged with divalent IgG. Tagged receptors were detected in Golgi stacks of approximately 50% of the cells analyzed. The position of the labeled cisternae within a given stack was found to be quite variable with cis and middle cisternae more often labeled at 5 min and trans cisternae at 30 min of antibody uptake. The finding that recycling plasmalemmal TFR can visit all or most Golgi subcompartments raises the likely possibility that any Golgi-associated posttranslational modification can occur during recycling as well as during the initial biosynthesis of plasmalemma receptors and other membrane proteins.

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Predescu, Sanda A., Dan N. Predescu, and George E. Palade. "Endothelial Transcytotic Machinery Involves Supramolecular Protein–Lipid Complexes." Molecular Biology of the Cell 12, no. 4 (April 2001): 1019–33. http://dx.doi.org/10.1091/mbc.12.4.1019.

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We have demonstrated that the plasmalemmal vesicles (caveolae) of the continuous microvascular endothelium function as transcytotic vesicular carriers for protein molecules >20 Å and that transcytosis is an N-ethylmaleimide–sensitive factor (NSF)-dependent, N-ethylmaleimide-sensitive process. We have further investigated NSF interactions with endothelial proteins to find out 1) whether a complete set of fusion and targeting proteins is present in the endothelium; 2) whether they are organized in multimolecular complexes as in neurons; and 3) whether the endothelial multimolecular complexes differ from their neuronal counterparts, because of their specialized role in transcytosis. To generate the complexes, we have used myc-NSF, cultured pulmonary endothelial cells, and rat lung cytosol and membrane preparations; to detect them we have applied coimmunoprecipitation with myc antibodies; and to characterize them we have used velocity sedimentation and cross-linking procedures. We have found that both cytosolic and membrane fractions contain complexes that comprise beside soluble NSF attachment proteins and SNAREs (soluble NSF attachment protein receptor), rab 5, dynamin, caveolin, and lipids. By immunogold labeling and negative staining we have detected in these complexes, myc-NSF, syntaxin, dynamin, caveolin, and endogenous NSF. Similar complexes are formed by endogenous NSF. The results indicate that complexes with a distinct protein–lipid composition exist and suggest that they participate in targeting, fusion, and fission of caveolae with the endothelial plasmalemma.

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Findlay, N., and GP Findlay. "Single Ion Channel Current Data from the Plasmalemma of Cytoplasmic Fragments of the Green Alga, Hydrodictyon africanum." Functional Plant Biology 22, no. 4 (1995): 571. http://dx.doi.org/10.1071/pp9950571.

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To measure, by patch clamping, electric current through ion channels in the plasmalemma of plant cells, access to the membrane surface is required. In higher plants, this access is gained by the preparation of protoplasts by enzymic methods. In plants such as the freshwater alga Hydrodictyon africanum, which have large cells, the preparation of protoplasts by enzymic methods is not possible. In this paper we describe a non-enzymic method for gaining access to the plasmalemma of Hydrodictyon. Our initial attempts to gain access to the plasmalemma of these cells by first plasmolysing the cells, and then cutting a window in the wall, so exposing the plasmalemma, were not successful. It was possible, however, after drying the cells in air, to cut them open and obtain fragments of the cytoplasm which maintain their original curvature. Standard patch clamping methods were then used to measure currents through single ion channels in the membrane, presumed to be the plasmalemma, bounding the outer surface of the fragments, although the success rate was low. Two types of channels were observed: (a) a multistate channel whose ion specificity was not established, and which in attached patches behaved as an outward current rectifier, and in a detached patch, as both inward and outward rectifier; and (b) a Cl- channel.

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44

Etxeberria, Ed, Pedro Gonzalez, and Javier Pozueta-Romero. "Sucrose Transport into Citrus Juice Cells: Evidence for an Endocytic Transport System." Journal of the American Society for Horticultural Science 130, no. 2 (March 2005): 269–74. http://dx.doi.org/10.21273/jashs.130.2.269.

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To investigate the mechanisms of sucrose transport and its accumulation into `Murcott' mandarin (Citrus reticulata Blanco) fruit, developmental changes in determinants of sink strength such as sucrose metabolizing enzymes, and sucrose transport across both plasmalemma and tonoplast were analyzed. Concurrently with sucrose levels, sucrose synthase, sucrose phosphate synthase and sucrose phosphate phosphatase increased throughout fruit development. Plasmalemma and tonoplast vesicles isolated from fruit collected at different developmental stages were analyzed for their transport capabilities. Sucrose uptake into energized plasmalemma vesicles was abolished by gramicidin, which is in accordance with the presence of an active symport mechanism of sucrose transport from the apoplast into the cytosol. Unexpectedly, tonoplast vesicles were shown to lack active transport mechanism of sucrose into the vacuole. More importantly, however, and in conformity with recent findings showing the occurrence of an endocytic mechanism of ion uptake in maize (Zea mays L.) root cells, citrus (Citrus L.) juice cells were shown to incorporate membrane impermeable dyes into their vacuoles in the presence of sucrose. High definition confocal microscopy revealed the co-localization of membrane impermeable markers in cytoplasmic vesicles and the formation of vesicles at the plasmalemma. The data provide evidence for an endocytic system of transport that allows direct incorporation of sucrose from the apoplast to the vacuole bypassing both the plasmalemma and tonoplast.

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Rao, K. S., and A. M. Catesson. "Changes in the membrane components of nondividing cambial cells." Canadian Journal of Botany 65, no. 2 (February 1, 1987): 246–54. http://dx.doi.org/10.1139/b87-035.

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Horse-chestnut cambial cells are characterized by the formation of numerous plasmalemma invaginations and the accumulation of membrane whorls in the vacuoles during the transition from activity to rest. This suggests an active membrane trafficking which was investigated with conventional electron microscopy methods combined with selective cytochemical staining. After the cessation of meristematic activity, cell wall thickening is accompanied by increased dictyosome activity. The incorporation of dictyosome vesicles into the plasma membrane produces an increase in plasmalemma surface area in these nongrowing cells. This increase is compensated for by endocytosis accomplished by the formation of saclike plasmalemma invaginations into the peripheral cytoplasm. These invaginations often contain vesicles and tubules. When these invaginations come in contact with a vacuole, they appear to push the tonoplast into the vacuole and form double-membrane protrusions which may eventually separate from the plasmalemma. ER cisternae situated in the intermembrane zone also appear to be transported into the vacuole. Other cisternae may be directly sequestered into the vacuole or take part in the formation of the myelinlike structures which were observed in the cytoplasm. Thus, the vacuoles appear to fill progressively with complex membranous structures of various origins (plasmalemma, tonoplast, ER). It is suggested that their subsequent disappearance during the winter is a consequence of the hydrolytic action of vacuolar contents.

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Ross, Brian L., and Jin Zhang. "Superresolution Plasmalemmal Lipid Mapping." Biophysical Journal 106, no. 2 (January 2014): 302a. http://dx.doi.org/10.1016/j.bpj.2013.11.1756.

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Bao, Li, Krassimira Hadjiolova, William A. Coetzee, and Michael J. Rindler. "Endosomal KATP channels as a reservoir after myocardial ischemia: a role for SUR2 subunits." American Journal of Physiology-Heart and Circulatory Physiology 300, no. 1 (January 2011): H262—H270. http://dx.doi.org/10.1152/ajpheart.00857.2010.

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ATP-sensitive K+ (KATP) channels, composed of inward rectifier K+ (Kir)6.x and sulfonylurea receptor (SUR)x subunits, are expressed on cellular plasma membranes. We demonstrate an essential role for SUR2 subunits in trafficking KATP channels to an intracellular vesicular compartment. Transfection of Kir6.x/SUR2 subunits into a variety of cell lines (including h9c2 cardiac cells and human coronary artery smooth muscle cells) resulted in trafficking to endosomal/lysosomal compartments, as assessed by immunofluorescence microscopy. By contrast, SUR1/Kir6.x channels efficiently localized to the plasmalemma. The channel turnover rate was similar with SUR1 or SUR2, suggesting that the expression of Kir6/SUR2 proteins in lysosomes is not associated with increased degradation. Surface labeling of hemagglutinin-tagged channels demonstrated that SUR2-containing channels dynamically cycle between endosomal and plasmalemmal compartments. In addition, Kir6.2 and SUR2 subunits were found in both endosomal and sarcolemmal membrane fractions isolated from rat hearts. The balance of these KATP channel subunits shifted to the sarcolemmal membrane fraction after the induction of ischemia. The KATP channel current density was also increased in rat ventricular myocytes isolated from hearts rendered ischemic before cell isolation without corresponding changes in subunit mRNA expression. We conclude that an intracellular pool of SUR2-containing KATP channels exists that is derived by endocytosis from the plasma membrane. In cardiac myocytes, this pool can potentially play a cardioprotective role by serving as a reservoir for modulating surface KATP channel density under stress conditions, such as myocardial ischemia.

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Abesinghe, Arambage, and James O. Garner. "FATTY ACID COMPOSITION OF PLASMALEMMA LIPIDS ASSOCIATED WITH GENETIC VARIABILITY IN COLD TOLERANCE OF SWEETPOTATO IPOMOEA BATATAS. (L). LAM." HortScience 30, no. 3 (June 1995): 441e—441. http://dx.doi.org/10.21273/hortsci.30.3.441e.

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Storage roots of `Beauregard' and `Centennial' were used to identify varietal differences in fatty acid composition in plasmalemma lipids during storage conditions. Total plasmalemma fatty acid composition of glycolipids and phospholipids in storage roots of `Beauregard' and `Centennial' did not differ. The fatty acid composition of MGDG and DGDG in storage root plasmalemma was >50% unsaturated fatty acids in `Beauregard'. The high percentage of 18:2 (65.44%) fatty acid compared to `Centennial' (19.70%) and 79.35% total unsaturated fatty acid content in MGDG may contribute to low temperature tolerance in `Beauregard'. The higher percentages of 16:1 and 22:1 fatty acids in `Centennial' compared to `Beauregard' contributed to MGDG fatty acid unsaturation. However, these fatty acids have not been related to chilling tolerance.

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Rubinstein, Bernard, A. I. Stern, and J. D. C. Chalmers. "Measurements of redox activity at the plasmalemma." Physiologia Plantarum 80, no. 3 (November 1990): 479–86. http://dx.doi.org/10.1034/j.1399-3054.1990.800323.x.

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KOURIE, J. I., and G. P. FINDLAY. "Ionic Currents across the Plasmalemma ofChara inflataCells." Journal of Experimental Botany 41, no. 2 (1990): 141–50. http://dx.doi.org/10.1093/jxb/41.2.141.

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Journal articles on the topic 'Plasmalema'

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