Journal articles: 'Octapeptide c terminal'

1

Yu, Kun-Hua, Mei-Yu Huang, Yi-Ru Lee, Yu-Kie Lin, Hau-Ren Chen, and Cheng-I. Lee. "The Effect of Octapeptide Repeats on Prion Folding and Misfolding." International Journal of Molecular Sciences 22, no. 4 (2021): 1800. http://dx.doi.org/10.3390/ijms22041800.

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Misfolding of prion protein (PrP) into amyloid aggregates is the central feature of prion diseases. PrP has an amyloidogenic C-terminal domain with three α-helices and a flexible tail in the N-terminal domain in which multiple octapeptide repeats are present in most mammals. The role of the octapeptides in prion diseases has previously been underestimated because the octapeptides are not located in the amyloidogenic domain. Correlation between the number of octapeptide repeats and age of onset suggests the critical role of octapeptide repeats in prion diseases. In this study, we have investigated four PrP variants without any octapeptides and with 1, 5 and 8 octapeptide repeats. From the comparison of the protein structure and the thermal stability of these proteins, as well as the characterization of amyloids converted from these PrP variants, we found that octapeptide repeats affect both folding and misfolding of PrP creating amyloid fibrils with distinct structures. Deletion of octapeptides forms fewer twisted fibrils and weakens the cytotoxicity. Insertion of octapeptides enhances the formation of typical silk-like fibrils but it does not increase the cytotoxicity. There might be some threshold effect and increasing the number of peptides beyond a certain limit has no further effect on the cell viability, though the reasons are unclear at this stage. Overall, the results of this study elucidate the molecular mechanism of octapeptides at the onset of prion diseases.

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RAJH, HUBERTUS M., EDWIN C. M. MARIMAN, GODEFRIDUS I. TESSER, and RUTGER J. F. NIVARD. "TRYPTOPHAN REPLACEMENT IN THE C-TERMINAL OCTAPEPTIDE OF CCK-PZ." International Journal of Peptide and Protein Research 15, no. 3 (2009): 200–210. http://dx.doi.org/10.1111/j.1399-3011.1980.tb02569.x.

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LOBO-HAJDU, Gisele, Hans-Peter BRAUN, Nancy ROMP, Leslie A. GRIVELL, Jan A. BERDEN, and Udo K. SCHMITZ. "Subunit VII of ubiquinol:cytochrome-c oxidoreductase from Neurospora crassa is functional in yeast and has an N-terminal extension that is not essential for mitochondrial targeting." Biochemical Journal 320, no. 3 (1996): 769–75. http://dx.doi.org/10.1042/bj3200769.

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cDNA clones encoding subunit VII of the Neurospora crassa bc1 complex (ubiquinol:cytochrome-c oxidoreductase), which is homologous with subunit VIII of the complex from yeast (encoded by QCR8), were identified on the basis of functional complementation of a yeast QCR8 deletion strain. The clones contain an open reading frame encoding a protein with a calculated molecular mass of 11.8 kDa. The N-terminal eight residues of the amino acid sequence deduced from the cDNA clones are absent from the mature protein, as revealed by direct sequencing of the isolated protein. To investigate the potential role of the N-terminal octapeptide in mitochondrial targeting, constructs were made encoding the precursor and the mature form of subunit VII from Neurospora. Incubation of isolated mitochondria with the two proteins revealed that the N-terminal extension of the precursor is removed on import. However, the presequence does not encode information for targeting, as the proteins encoded by both constructs can be imported into isolated mitochondria with equal efficiency. In contrast, the octapeptide seems to have functional importance: the defect in the yeast qcr8-null mutant is not complemented on transformation with the construct encoding mature subunit VII from N. crassa in a single-copy plasmid. We therefore speculate that the N-terminal extension plays a role in intramitochondrial sorting of N. crassa subunit VII. This is supported by the fact that the subunit VII precursor is processed by a protease other than the general mitochondrial processing peptidase. Interestingly, the presequence of N. crassa subunit VII has an amino acid composition similar to the octapeptides cleaved off by the mitochondrial intermediate peptidase.

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Isaya, G., F. Kalousek, W. A. Fenton, and L. E. Rosenberg. "Cleavage of precursors by the mitochondrial processing peptidase requires a compatible mature protein or an intermediate octapeptide." Journal of Cell Biology 113, no. 1 (1991): 65–76. http://dx.doi.org/10.1083/jcb.113.1.65.

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Many precursors of mitochondrial proteins are processed in two successive steps by independent matrix peptidases (MPP and MIP), whereas others are cleaved in a single step by MPP alone. To explain this dichotomy, we have constructed deletions of all or part of the octapeptide characteristic of a twice cleaved precursor (human ornithine transcarbamylase [pOTC]), have exchanged leader peptide sequences between once-cleaved (human methylmalonyl-CoA mutase [pMUT]; yeast F1ATPase beta-subunit [pF1 beta]) and twice-cleaved (pOTC; rat malate dehydrogenase (pMDH); Neurospora ubiquinol-cytochrome c reductase iron-sulfur subunit [pFe/S]) precursors, and have incubated these proteins with purified MPP and MIP. When the octapeptide of pOTC was deleted, or when the entire leader peptide of a once-cleaved precursor (pMUT or pF1 beta) was joined to the mature amino terminus of a twice-cleaved precursor (pOTC or pFe/S), no cleavage was produced by either protease. Cleavage of these constructs by MPP was restored by re-inserting as few as two amino-terminal residues of the octapeptide or of the mature amino terminus of a once-cleaved precursor. We conclude that the mature amino terminus of a twice-cleaved precursor is structurally incompatible with cleavage by MPP; such proteins have evolved octapeptides cleaved by MIP to overcome this incompatibility.

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Jarrousse, C., H. Niel, M. P. Audousset-Puech, J. Martinez, and D. Bataille. "Oxyntomodulin and its C-terminal octapeptide inhibit liquid meal-stimulated acid secretion." Peptides 7 (January 1986): 253–56. http://dx.doi.org/10.1016/0196-9781(86)90196-8.

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Jarrousse, Claire, Marie-Pascale Audousset-Puech, Marcelle Dubrasquet, Huguette Niel, Jean Martinez, and Dominique Bataille. "Oxyntomodulin (glucagon-37) and its C-terminal octapeptide inhibit gastric acid secretion." FEBS Letters 188, no. 1 (1985): 81–84. http://dx.doi.org/10.1016/0014-5793(85)80879-6.

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7

Hara, Hideyuki, and Suehiro Sakaguchi. "N-Terminal Regions of Prion Protein: Functions and Roles in Prion Diseases." International Journal of Molecular Sciences 21, no. 17 (2020): 6233. http://dx.doi.org/10.3390/ijms21176233.

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The normal cellular isoform of prion protein, designated PrPC, is constitutively converted to the abnormally folded, amyloidogenic isoform, PrPSc, in prion diseases, which include Creutzfeldt-Jakob disease in humans and scrapie and bovine spongiform encephalopathy in animals. PrPC is a membrane glycoprotein consisting of the non-structural N-terminal domain and the globular C-terminal domain. During conversion of PrPC to PrPSc, its 2/3 C-terminal region undergoes marked structural changes, forming a protease-resistant structure. In contrast, the N-terminal region remains protease-sensitive in PrPSc. Reverse genetic studies using reconstituted PrPC-knockout mice with various mutant PrP molecules have revealed that the N-terminal domain has an important role in the normal function of PrPC and the conversion of PrPC to PrPSc. The N-terminal domain includes various characteristic regions, such as the positively charged residue-rich polybasic region, the octapeptide repeat (OR) region consisting of five repeats of an octapeptide sequence, and the post-OR region with another positively charged residue-rich polybasic region followed by a stretch of hydrophobic residues. We discuss the normal functions of PrPC, the conversion of PrPC to PrPSc, and the neurotoxicity of PrPSc by focusing on the roles of the N-terminal regions in these topics.

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8

Monk, Brian C., Kyoko Niimi, Susan Lin, et al. "Surface-Active Fungicidal d-Peptide Inhibitors of the Plasma Membrane Proton Pump That Block Azole Resistance." Antimicrobial Agents and Chemotherapy 49, no. 1 (2005): 57–70. http://dx.doi.org/10.1128/aac.49.1.57-70.2005.

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ABSTRACT A 1.8-million-member d-octapeptide combinatorial library was constructed in which each member comprised a diversity-containing N-terminal pentapeptide and a C-terminal amidated triarginine motif. The C-terminal motif concentrated the library members at the fungal cell surface. A primary screen for inhibitors of Saccharomyces cerevisiae and Candida albicans growth, together with an in vitro secondary screen with the S. cerevisiae plasma membrane ATPase (Pma1p) as a target, identified the antifungal d-octapeptide BM0 (d-NH2-RFWWFRRR-CONH2). Optimization of BM0 led to the construction of BM2 (d-NH2-RRRFWWFRRR-CONH2), which had broad-spectrum fungicidal activity against S. cerevisiae, Candida species, and Cryptococcus neoformans; bound strongly to the surfaces of fungal cells; inhibited the physiological activity of Pma1p; and appeared to target Pma1p, with 50% inhibitory concentrations in the range of 0.5 to 2.5 μM. At sub-MICs (<5 μM), BM2 chemosensitized to fluconazole (FLC) S. cerevisiae strains functionally hyperexpressing fungal lanosterol 14α-demethylase and resistance-conferring transporters of azole drugs. BM2 chemosensitized to FLC some FLC-resistant clinical isolates of C. albicans and C. dubliniensis and chemosensitized to itraconazole clinical isolates of C. krusei that are intrinsically resistant to FLC. The growth-inhibitory concentrations of BM2 did not cause fungal cell permeabilization, significant hemolysis of red blood cells, or the death of cultured HEp-2 epithelial cells. BM2 represents a novel class of broad-spectrum, surface-active, Pma1p-targeting fungicides which increases the potencies of azole drugs and circumvents azole resistance.

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9

GILLESSEN, DIETER, ARNOLD TRZECIAK, RITA K. M. MÜLLER, and ROLF O. STUDER. "SYNTHESES AND BIOLOGICAL ACTIVITIES OF METHOXININE-ANALOGUES OF THE C-TERMINAL OCTAPEPTIDE OF CHOLECYSTOKININ-PANCREOZYMIN." International Journal of Peptide and Protein Research 13, no. 2 (2009): 130–36. http://dx.doi.org/10.1111/j.1399-3011.1979.tb01860.x.

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10

Dubrasquet, J. M., M. P. Audousset-Puech, J. Martinez, and D. Bataille. "Somatostatin enhances the inhibitory effect of oxyntomodulin and its C-terminal octapeptide on acid secretion." Peptides 7 (January 1986): 257–59. http://dx.doi.org/10.1016/0196-9781(86)90197-x.

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11

Dmitriev, Igor P., Elena A. Kashentseva, and David T. Curiel. "Engineering of Adenovirus Vectors Containing Heterologous Peptide Sequences in the C Terminus of Capsid Protein IX." Journal of Virology 76, no. 14 (2002): 6893–99. http://dx.doi.org/10.1128/jvi.76.14.6893-6899.2002.

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ABSTRACT The utility of the present generation of adenovirus (Ad) vectors for gene therapy applications could be improved by restricting native viral tropism to selected cell types. In order to achieve modification of Ad tropism, we proposed to exploit a minor component of viral capsid, protein IX (pIX), for genetic incorporation of targeting ligands. Based on the proposed structure of pIX, we hypothesized that its C terminus could be used as a site for incorporation of heterologous peptide sequences. We engineered recombinant Ad vectors containing modified pIX carrying a carboxy-terminal Flag epitope along with a heparan sulfate binding motif consisting of either eight consecutive lysines or a polylysine sequence. Using an anti-Flag antibody, we have shown that modified pIXs are incorporated into virions and display Flag-containing C-terminal sequences on the capsid surface. In addition, both lysine octapeptide and polylysine ligands were accessible for binding to heparin-coated beads. In contrast to virus bearing lysine octapeptide, Ad vector displaying a polylysine was capable of recognizing cellular heparan sulfate receptors. We have demonstrated that incorporation of a polylysine motif into the pIX ectodomain results in a significant augmentation of Ad fiber knob-independent infection of CAR-deficient cell types. Our data suggest that the pIX ectodomain can serve as an alternative to the fiber knob, penton base, and hexon proteins for incorporation of targeting ligands for the purpose of Ad tropism modification.

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12

Sachs, A. B., R. W. Davis, and R. D. Kornberg. "A single domain of yeast poly(A)-binding protein is necessary and sufficient for RNA binding and cell viability." Molecular and Cellular Biology 7, no. 9 (1987): 3268–76. http://dx.doi.org/10.1128/mcb.7.9.3268.

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The poly(A)-binding protein (PAB) gene of Saccharomyces cerevisiae is essential for cell growth. A 66-amino acid polypeptide containing half of a repeated N-terminal domain can replace the entire protein in vivo. Neither an octapeptide sequence conserved among eucaryotic RNA-binding proteins nor the C-terminal domain of PAB is required for function in vivo. A single N-terminal domain is nearly identical to the entire protein in the number of high-affinity sites for poly(A) binding in vitro (one site with an association constant of approximately 2 X 10(7) M-1) and in the size of the binding site (12 A residues). Multiple N-terminal domains afford a mechanism of PAB transfer between poly(A) strands.

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13

Sachs, A. B., R. W. Davis, and R. D. Kornberg. "A single domain of yeast poly(A)-binding protein is necessary and sufficient for RNA binding and cell viability." Molecular and Cellular Biology 7, no. 9 (1987): 3268–76. http://dx.doi.org/10.1128/mcb.7.9.3268-3276.1987.

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The poly(A)-binding protein (PAB) gene of Saccharomyces cerevisiae is essential for cell growth. A 66-amino acid polypeptide containing half of a repeated N-terminal domain can replace the entire protein in vivo. Neither an octapeptide sequence conserved among eucaryotic RNA-binding proteins nor the C-terminal domain of PAB is required for function in vivo. A single N-terminal domain is nearly identical to the entire protein in the number of high-affinity sites for poly(A) binding in vitro (one site with an association constant of approximately 2 X 10(7) M-1) and in the size of the binding site (12 A residues). Multiple N-terminal domains afford a mechanism of PAB transfer between poly(A) strands.

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14

Galas, M. C., M. F. Lignon, M. Rodriguez, et al. "Structure-activity relationship studies on cholecystokinin: analogues with partial agonist activity." American Journal of Physiology-Gastrointestinal and Liver Physiology 254, no. 2 (1988): G176—G182. http://dx.doi.org/10.1152/ajpgi.1988.254.2.g176.

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In the present study, hepta- and octapeptide analogues of the C-terminal part of cholecystokinin, modified on the C-terminal phenylalanine residue, were synthesized. CCK analogues were prepared in which the peptide bond between aspartic acid and phenylalanine had or had not been modified and were lacking the C-terminal primary amide function. These CCK derivatives were able to cause full stimulation of amylase release from rat pancreatic acini but without a decrease in amylase release at supramaximal concentrations. There was a close relationship between the abilities of these derivatives to stimulate amylase release and their abilities to inhibit binding of 125I-BH-CCK-9 to CCK receptors on rat and guinea pig pancreatic acini. These CCK analogues were also able to recognize the guinea pig brain CCK receptors, some of them being particularly potent. The findings indicate that the aromatic ring of phenylalanine is important for the binding to brain and pancreatic CCK receptors, whereas the C-terminal primary amide function is not essential for the binding to pancreatic CCK receptors but is crucial for biological activity of rat pancreatic acini.

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15

Martin, Christine M., Vadivel Parthsarathy, Annie Hasib, et al. "Biological Activity and Antidiabetic Potential of C-Terminal Octapeptide Fragments of the Gut-Derived Hormone Xenin." PLOS ONE 11, no. 3 (2016): e0152818. http://dx.doi.org/10.1371/journal.pone.0152818.

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16

Jarrousse, Claire, Marie-Pascale Audousset-Puech, Marcelle Dubrasquet, Huguette Niel, Jean Martinez, and Dominique Bataille. "Comparative study of oxyntomodulin and its C-terminal octapeptide on the gastric acid secretion in rat." Regulatory Peptides 10 (January 1985): S35. http://dx.doi.org/10.1016/0167-0115(85)90346-5.

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17

Loomis, Ronald E., Ping-Cheung Lee, and Ching-Chung Tseng. "Conformational analysis of the cholecystokinin C-terminal octapeptide: a nuclear magnetic resonance and computer-simulation approach." Biochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology 911, no. 2 (1987): 168–79. http://dx.doi.org/10.1016/0167-4838(87)90006-9.

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18

Dyrberg, T., and M. B. Oldstone. "Peptides as antigens. Importance of orientation." Journal of Experimental Medicine 164, no. 4 (1986): 1344–49. http://dx.doi.org/10.1084/jem.164.4.1344.

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Factors known to be important in producing protein-reactive peptide antibodies include the accessibility of the region from which the peptide sequence is derived, the hydrophilic-phobic character of the sequence, and the length of the peptide. The data presented here indicate that the orientation of the peptide coupled to a carrier protein also influences the binding pattern of peptide antibodies. An octapeptide, representing a sequence from the alpha chain of the human acetylcholine receptor, was coupled either through an N- or C-terminal cysteine-glycine-glycine linker to a carrier protein and used to immunize rabbits. The resulting antisera reacted at comparable titers to the uncoupled immunizing peptides, but did not crossreact with the identical but opposite-linked peptide. Characterization of the binding to other homologous peptides showed that immunization with the N-terminal-linked peptide induced antibodies reactive specifically with the C-terminal amino acid(s). Immunization with the C-linked peptide resulted in antibodies reactive with a site of the peptide near the C-terminus.

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19

SHIRAISHI, Noriyuki, Yoko INAI, Wenxiang BI, and Morimitsu NISHIKIMI. "Fragmentation and dimerization of copper-loaded prion protein by copper-catalysed oxidation." Biochemical Journal 387, no. 1 (2005): 247–55. http://dx.doi.org/10.1042/bj20041561.

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Prion protein consists of an N-terminal domain containing a series of octapeptide repeats with the consensus sequence PHGGGWGQ and a C-terminal domain composed of three α-helices and two short β-strands. Several studies have shown that the N-terminal domain binds five Cu2+ ions. In the present study, we have investigated copper-catalysed oxidation of a recombinant mouse prion protein, PrP23–231. The copper-loaded PrP23–231 was found to be carbonylated by incubation with dopamine. Besides the formation of carbonyls, a cross-linked species with the dimeric size and C-terminally truncated species were generated. These reactions were retarded in the presence of Cu+- and Cu2+-specific copper chelators, catalase, and SOD (superoxide dismutase), but not in the presence of various bivalent metal ions. Together, these results indicate that the copper bound to prion protein undergoes catalytic cycling in the presence of catecholamines and causes the oxidation of the protein.

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20

Wells, Mark A., Graham S. Jackson, Samantha Jones, et al. "A reassessment of copper(II) binding in the full-length prion protein." Biochemical Journal 399, no. 3 (2006): 435–44. http://dx.doi.org/10.1042/bj20060458.

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It has been shown previously that the unfolded N-terminal domain of the prion protein can bind up to six Cu2+ ions in vitro. This domain contains four tandem repeats of the octapeptide sequence PHGGGWGQ, which, alongside the two histidine residues at positions 96 and 111, contribute to its Cu2+ binding properties. At the maximum metal-ion occupancy each Cu2+ is co-ordinated by a single imidazole and deprotonated backbone amide groups. However two recent studies of peptides representing the octapeptide repeat region of the protein have shown, that at low Cu2+ availability, an alternative mode of co-ordination occurs where the metal ion is bound by multiple histidine imidazole groups. Both modes of binding are readily populated at pH 7.4, while mild acidification to pH 5.5 selects in favour of the low occupancy, multiple imidazole binding mode. We have used NMR to resolve how Cu2+ binds to the full-length prion protein under mildly acidic conditions where multiple histidine co-ordination is dominant. We show that at pH 5.5 the protein binds two Cu2+ ions, and that all six histidine residues of the unfolded N-terminal domain and the N-terminal amine act as ligands. These two sites are of sufficient affinity to be maintained in the presence of millimolar concentrations of competing exogenous histidine. A previously unknown interaction between the N-terminal domain and a site on the C-terminal domain becomes apparent when the protein is loaded with Cu2+. Furthermore, the data reveal that sub-stoichiometric quantities of Cu2+ will cause self-association of the prion protein in vitro, suggesting that Cu2+ may play a role in controlling oligomerization in vivo.

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21

Veyrac, M., D. Ribard, J. P. Daures, et al. "Inhibitory Effect of the C-Terminal Octapeptide of Oxyntomodulin on Pentagastrin-Stimulated Gastric Acid Secretion in Man." Scandinavian Journal of Gastroenterology 24, no. 10 (1989): 1238–42. http://dx.doi.org/10.3109/00365528909090793.

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22

Calam, J., D. Gordon, W. S. Peart, S. A. Taylor, and R. J. Unwin. "Renal effects of gastrin C-terminal tetrapeptide (as pentagastrin) and cholecystokinin octapeptide in conscious rabbit and man." British Journal of Pharmacology 91, no. 2 (1987): 307–14. http://dx.doi.org/10.1111/j.1476-5381.1987.tb10285.x.

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23

Kim, Chan-Lan, Ayako Karino, Naotaka Ishiguro, Morikazu Shinagawa, Motoyoshi Sato, and Motohiro Horiuchi. "Cell-surface retention of PrPC by anti-PrP antibody prevents protease-resistant PrP formation." Journal of General Virology 85, no. 11 (2004): 3473–82. http://dx.doi.org/10.1099/vir.0.80113-0.

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The C-terminal portion of the prion protein (PrP), corresponding to a protease-resistant core fragment of the abnormal isoform of the prion protein (PrPSc), is essential for prion propagation. Antibodies to the C-terminal portion of PrP are known to inhibit PrPSc accumulation in cells persistently infected with prions. Here it was shown that, in addition to monoclonal antibodies (mAbs) to the C-terminal portion of PrP, a mAb recognizing the octapeptide repeat region in the N-terminal part of PrP that is dispensable for PrPSc formation reduced PrPSc accumulation in cells persistently infected with prions. The 50 % effective dose was as low as ∼1 nM, and, regardless of their epitope specificity, the inhibitory mAbs shared the ability to bind cellular prion protein (PrPC) expressed on the cell surface. Flow cytometric analysis revealed that mAbs that bound to the cell surface during cell culture were not internalized even after their withdrawal from the growth medium. Retention of the mAb–PrPC complex on the cell surface was also confirmed by the fact that internalization was enhanced by treatment of cells with dextran sulfate. These results suggested that anti-PrP mAb antagonizes PrPSc formation by interfering with the regular PrPC degradation pathway.

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Ho, Wen-Zhe, George Stavropoulos, Jian-Ping Lai та ін. "Substance P C-terminal octapeptide analogues augment tumor necrosis factor-α release by human blood monocytes and macrophages". Journal of Neuroimmunology 82, № 2 (1998): 126–32. http://dx.doi.org/10.1016/s0165-5728(97)00175-6.

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25

FULCRAND, PIERRE, MARC RODRIGUEZ, MARIE-CHRISTINE GALAS, et al. "2-Phenylethyl ester and 2-phenylethyl amide derivative analogues of the C-terminal hepta- and octapeptide of cholecystokinin." International Journal of Peptide and Protein Research 32, no. 5 (2009): 384–95. http://dx.doi.org/10.1111/j.1399-3011.1988.tb01273.x.

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LO, WILLIAM W. Y., COLIN R. CLARK, and JOHN HUGHES. "Activation of polyphosphoinositide metabolism by the C-terminal octapeptide of cholecystokinin in a human embryonic pituitary cell line." Biochemical Society Transactions 14, no. 6 (1986): 1108–9. http://dx.doi.org/10.1042/bst0141108a.

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27

Greenberg, D., G. P. Smith, and J. Gibbs. "Infusion of CCK-8 into hepatic-portal vein fails to reduce food intake in rats." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 252, no. 5 (1987): R1015—R1018. http://dx.doi.org/10.1152/ajpregu.1987.252.5.r1015.

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If the putative satiating effect of endogenous cholecystokinin (CCK) is produced through a circulating hormonal mechanism, then administration of exogenous CCK into the hepatic-portal vein should decrease meal size. To test this, one form of endogenous CCK, the C-terminal octapeptide CCK-8, was infused intraportally in doses of 4 and 8 micrograms/kg just prior to a test meal. Neither dose decreased food intake after intraportal infusion even though intraperitoneal administration of 4 micrograms/kg CCK-8 decreased meal size approximately 50% in the same rats. The results suggest that if endogenous CCK-8 has a satiating effect, it acts primarily through a paracrine mechanism.

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28

AUMELAS, ANDRÉ, MARIE-PASCALE AUDOUSSET-PUECH, ANNIE HEITZ, DOMINIQUE BATAILLE та JEAN MARTINEZ. "1H n.m.r. conformational studies on the C-terminal octapeptide of oxyntomodulin, a β-turn locked by a salt bridge". International Journal of Peptide and Protein Research 34, № 4 (2009): 268–76. http://dx.doi.org/10.1111/j.1399-3011.1989.tb01574.x.

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29

Dubrasquet, M., M. P. Audousset-Puech, J. Martinez, and D. Bataille. "Somatostatin enhances the inhibitory effect of glucagon-37/oxyntomodulin (OXM) and of its C-terminal octapeptide on acid secretion." Regulatory Peptides 10 (January 1985): S57. http://dx.doi.org/10.1016/0167-0115(85)90391-x.

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30

Lallement, Jean-Christophe, Jean-Claude Galleyrand, Ana-Christina Lima-Leite, Pierre Fulcrand, and Jean Martinez. "Gastrin13 and the C-terminal octapeptide of cholecystokinin are differently coupled to G-proteins in guinea-pig brain membranes." European Journal of Pharmacology: Molecular Pharmacology 267, no. 3 (1994): 297–305. http://dx.doi.org/10.1016/0922-4106(94)90154-6.

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31

Gardner, J. D., M. Knight, V. E. Sutliff, and R. T. Jensen. "N-terminal fragments of CCK-(26-33) as cholecystokinin receptor antagonists in guinea pig pancreatic acini." American Journal of Physiology-Gastrointestinal and Liver Physiology 248, no. 1 (1985): G98—G102. http://dx.doi.org/10.1152/ajpgi.1985.248.1.g98.

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In the present study we synthesized different N-terminal fragments and analogues of the C-terminal octapeptide of cholecystokinin [CCK-(26-33)] and examined their actions on dispersed acini prepared from guinea pig pancreas. None of the N-terminal fragments or analogues altered basal amylase release. Analogues of CCK-(26-32), CCK-(26-31), and CCK-(26-30) inhibited CCK-(26-33)-stimulated amylase, and there was a close correlation between the ability of an analogue to inhibit stimulated amylase and the analogue's ability to inhibit binding of 125I-cholecystokinin. N-acetyl-CCK-(26-29)-amide at concentrations as high as 100 microM did not inhibit CCK-(26-33)-stimulated amylase release or binding of 125I-CCK. For those analogues that antagonized CCK-(26-33)-stimulated amylase release the antagonism was of the competitive type and was specific for those secretagogues that interact with the cholecystokinin receptor. Removing the C-terminal amide from N-acetyl-CCK-(26-31)-amide caused a 10-fold decrease in the inhibitory potency, whereas removing the C-terminal amide from N-acetyl-CCK-(26-30)-amide did not alter the inhibitory potency of the peptide. Removing the sulfate ester from the tyrosine residue in position 27 of N-acetyl-CCK-(26-31) did not alter the inhibitory potency of the peptide, whereas removing the sulfate ester from the tyrosine residue in position 27 of N-acetyl-(26-30) caused a three- to fivefold decrease in the inhibitory potency of the peptide.(ABSTRACT TRUNCATED AT 250 WORDS)

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Song, Xiaosheng, Liuliu Yang, Mingzhu Wang, et al. "A higher-order configuration of the heterodimeric DOT1L–AF10 coiled-coil domains potentiates their leukemogenenic activity." Proceedings of the National Academy of Sciences 116, no. 40 (2019): 19917–23. http://dx.doi.org/10.1073/pnas.1904672116.

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Chromosomal translocations of MLL1 (Mixed Lineage Leukemia 1) yield oncogenic chimeric proteins containing the N-terminal portion of MLL1 fused with distinct partners. The MLL1–AF10 fusion causes leukemia through recruiting the H3K79 histone methyltransferase DOT1L via AF10’s octapeptide and leucine zipper (OM-LZ) motifs. Yet, the precise interaction sites in DOT1L, detailed interaction modes between AF10 and DOT1L, and the functional configuration of MLL1–AF10 in leukeomogenesis remain unknown. Through a combined approach of structural and functional analyses, we found that the LZ domain of AF10 interacts with the coiled-coil domains of DOT1L through a conserved binding mode and discovered that the C-terminal end of the LZ domain and the OM domain of AF10 mediate the formation of a DOT1L–AF10 octamer via tetramerization of the binary complex. We reveal that the oligomerization ability of the DOT1L–AF10 complex is essential for MLL1–AF10’s leukemogenic function. These findings provide insights into the molecular basis of pathogenesis by MLL1 rearrangements.

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33

Najdovski, Tome, Nadia Collette, and Monique Deschodt-Lanckman. "Hydrolysis of the C-terminal octapeptide of cholecystokinin by rat kidney membranes: Characterization of the cleavage by solubilized endopeptidase - 24.11." Life Sciences 37, no. 9 (1985): 827–34. http://dx.doi.org/10.1016/0024-3205(85)90517-x.

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Asada, N., and T. Kanno. "Influence of pH change on redox state and CCK-induced secretion in isolated perfused rat pancreas." American Journal of Physiology-Cell Physiology 248, no. 3 (1985): C235—C240. http://dx.doi.org/10.1152/ajpcell.1985.248.3.c235.

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The isolated perfused rat pancreas was used to examine the influence of the acid-base status of the perfusing solution on the redox states of cytochromes and secretory responses. Lowering the pH in a perfusing solution (pHe) from 7.3 to 6.8 induced simultaneous oxidation of cytochromes aa3, b, and c + c1, and further lowering to 6.0 induced larger oxidation of the cytochromes. Raising the pHe from 7.3 to 8.0 induced reduction of the cytochromes. Continuous stimulation with synthetic C-terminal octapeptide of cholecystokinin (CCK-8) at 100 pM induced the maximum secretory responses (pancreatic juice flow, protein output, and amylase output) during perfusion with the standard solution. The responses were not inhibited at pHe 6.8 but were inhibited significantly at pHe 6.0 or 8.0. The responses induced by stimulation with 20 pM CCK-8 were completely inhibited when pHe was lowered to 6.0 and CaCl2 was removed from the perfusing solution.

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35

Chowdhury, Vishwajit Sur, Takayoshi Ubuka, Tomohiro Osugi, Taichi Shimura, and Kazuyoshi Tsutsui. "Identification, localization and expression of LPXRFamide peptides, and melatonin-dependent induction of their precursor mRNA in the newt brain." Journal of Endocrinology 209, no. 2 (2011): 211–20. http://dx.doi.org/10.1530/joe-10-0494.

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The existence of RFamide peptides with a C-terminal LPXRFamide (X=L or Q) motif has been identified in the brain of various vertebrate species. However, the presence of LPXRFamide peptides in the urodele brain is not yet known. In this study, we cloned a cDNA encoding the precursor of LPXRFamide peptides from the newt brain by a combination of 3′ and 5′ rapid amplification of cDNA ends. The deduced LPXRFamide peptide precursor consisted of 233 amino acid residues, encoding four putative LPXRFamide peptides. All the peptide sequences were flanked by a glycine C-terminal amidation signal and basic amino acid on each end as an endoproteolytic site. Mass spectrometric analyses detected a nonapeptide, two decapeptides and an octapeptide produced from the precursor polypeptide in the brain as endogenous ligands. In situ hybridization further revealed the cellular localization of newt LPXRFamide (nLPXRFa) precursor mRNA in the suprachiasmatic nucleus (SCN) in the newt hypothalamus. Immunocytochemistry showed a cluster of cell bodies restricted to the SCN and their terminals in the median eminence. To understand the regulatory mechanism of nLPXRFa peptide expression, we further analyzed the effect of melatonin on the expression of nLPXRFa precursor mRNA. Melatonin administration to newts increased the expression of nLPXRFa precursor mRNA in the diencephalon. These results indicate that the urodele hypothalamus possesses LPXRFamide peptides and the expression of LPXRFamide peptides is regulated by melatonin. The localization of nLPXRFa peptides further suggests that these peptides may be involved in the regulation of pituitary hormone release in newts.

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36

Black, G. W., G. P. Hazlewood, G. P. Xue, C. G. Orpin, and H. J. Gilbert. "Xylanase B from Neocallimastix patriciarum contains a non-catalytic 455-residue linker sequence comprised of 57 repeats of an octapeptide." Biochemical Journal 299, no. 2 (1994): 381–87. http://dx.doi.org/10.1042/bj2990381.

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A Neocallimastix patriciarum cDNA library was screened for xylanase-expressing clones, which were distinct from the previously characterized N. patriciarum xynA cDNA encoding xylanase A. A single cDNA, designated xynB, which did not exhibit homology with xynA, was isolated. Northern-blot analysis of mRNA from Avicel-grown N. patriciarum showed that xynB hybridized to a 3.4 kb mRNA species. The nucleotide sequence of xynB revealed a single open reading frame of 2580 bp coding for a protein designated xylanase B (XYLB), of M(r) 88,066. The primary structure of XYLB was comprised of a 21-residue N-terminal signal peptide, followed by a 304-amino acid sequence that exhibited substantial homology with the catalytic domains of family F xylanases. The N-terminal domain was linked to a C-terminal 70-residue sequence by a putative linker region, comprising 12 tandem repeats of a sequence containing TLPG as the core sequence, followed by an octapeptide XSKTLPGG where X can be S, K or N, which was repeated in tandem 45 times. Truncated derivatives of xynB encoding the N-terminal 338 residues directed the synthesis of a functional xylanase, confirming that the region of XYLB, which exhibited homology with family F xylanases, constitutes the catalytic domain. To investigate the catalytic properties of XYLB, the catalytic domain was fused to the Escherichia coli maltose-binding protein, and the fusion protein purified by amylose affinity chromatography. The purified enzyme hydrolysed oat, rye and wheat arabinoxylan releasing primarily xylobiose, xylotriose and some xylose. The XYLB fusion did not cleave any cellulosic substrates. The data presented in this report suggest that the multiple xylanases of N. patriciarum arose, not through the duplication of a single gene, but by the transfer of distinct xylanase-encoding DNA sequences into the anaerobic fungus. The possible origin of the xynB gene is discussed.

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Jung, G., D. S. Louie, and C. Owyang. "Pancreatic polypeptide inhibits pancreatic enzyme secretion via a cholinergic pathway." American Journal of Physiology-Gastrointestinal and Liver Physiology 253, no. 5 (1987): G706—G710. http://dx.doi.org/10.1152/ajpgi.1987.253.5.g706.

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In rat pancreatic slices, rat pancreatic polypeptide (PP) or C-terminal hexapeptide of PP [PP-(31-36)] inhibited potassium-stimulated amylase release in a dose-dependent manner. The inhibition was unaffected by addition of hexamethonium but blocked by atropine. In contrast, PP(31-36) did not have any effect on acetylcholine- or cholecystokinin octapeptide-stimulated amylase release. In addition, when pancreatic slices were incubated with [3H] choline, PP(31-36) inhibited the potassium-evoked release of synthesized [3H] acetylcholine in a dose-dependent manner. The inhibitory action of PP was unaffected by adrenergic, dopaminergic, or opioid receptor antagonists. Thus PP inhibits pancreatic enzyme secretion via presynaptic modulation of acetylcholine release. This newly identified pathway provides a novel mechanism for hormonal inhibition of pancreatic enzyme secretion via modulation of the classic neurotransmitter function.

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38

Reidelberger, R. D. "Abdominal vagal mediation of the satiety effects of exogenous and endogenous cholecystokinin in rats." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 263, no. 6 (1992): R1354—R1358. http://dx.doi.org/10.1152/ajpregu.1992.263.6.r1354.

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The hypothesis that peripherally administered cholecystokinin C-terminal octapeptide (CCK-8) and endogenous CCK act by the same abdominal vagal mechanism to produce satiety was tested by injecting rats with CCK-8 or the type A CCK receptor antagonist MK-329 after they had received bilateral subdiaphragmatic vagotomies. CCK-8 (8 nmol/kg ip) inhibited 1-h food intake by 60%; vagotomy and MK-329 (0.5 mg/kg sc) each completely blocked this effect. In contrast, vagotomy did not alter the stimulatory effect of MK-329 (0.5 mg/kg sc) on feeding; 3-h cumulative intake in control and vagotomized animals was increased by 25 and 34%, respectively. These results suggest that satiety is mediated in part by an endogenous CCK action that is independent of abdominal vagal innervation.

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39

Oiry, Catherine, Jean-Claude Galleyrand, Ana-Christina Lima-Leite, Pierre Fulcrand, and Jean Martinez. "Are C-terminal octapeptide of cholecystokinin and [Leu11]gastrin-(5–17) different in stimulating acid secretion in isolated rabbit gastric glands?" European Journal of Pharmacology 294, no. 2-3 (1995): 511–19. http://dx.doi.org/10.1016/0014-2999(95)00574-9.

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40

Lu, YQ, ME Nichols, WL Bigbee, RL Nagel, and OO Blumenfeld. "Structural polymorphism of glycophorins demonstrated by immunoblotting techniques." Blood 69, no. 2 (1987): 618–24. http://dx.doi.org/10.1182/blood.v69.2.618.618.

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Abstract We have explored the polymorphism of the glycophorin system in the human erythrocyte membrane using the immunoblotting techniques and examining 52 individuals selected without prior bias as to their serologic state and ten documented serologic variants of M, N, S, s blood group system. Polyclonal antisera to alpha glycophorin and to alpha glycophorin CNBr carboxyl terminal fragment C (residues 82–131) and M and N specific monoclonal antibodies (MoAbs) were used. The first two reagents detect specific regions of the alpha glycophorin molecule and all electrophoretically resolved species of glycophorins immunologically related to alpha and delta glycophorins (delta glycophorin, [alpha-delta] hybrids and other glycophorins with an alteration in the carboxyl terminal segment); the M and N MoAbs identified the glycophorin species containing or lacking the M or N determinant in the amino terminal octapeptide structures. We find that immunoblotting confirmed in all cases the serologically determined phenotype; we also find that polymorphic forms of the glycophorin system are relatively infrequent; immunoblotting, independent from serologic testing, was capable of detecting five mutants, two most likely S-s-U-phenotypes; a new glycophorin species was detected in normal red cells with both antiglycophorin and antipeptide C sera, which is not evident with MoAbs; immunoblots of known glycophorin variants (En(a-), U-, Mg, Mi I, II, III, V, and Sta) confirmed but also extended our knowledge of the abnormal glycophorins involved; and the He+ and Wrb(-) cells showed normal patterns.

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41

Lu, YQ, ME Nichols, WL Bigbee, RL Nagel, and OO Blumenfeld. "Structural polymorphism of glycophorins demonstrated by immunoblotting techniques." Blood 69, no. 2 (1987): 618–24. http://dx.doi.org/10.1182/blood.v69.2.618.bloodjournal692618.

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We have explored the polymorphism of the glycophorin system in the human erythrocyte membrane using the immunoblotting techniques and examining 52 individuals selected without prior bias as to their serologic state and ten documented serologic variants of M, N, S, s blood group system. Polyclonal antisera to alpha glycophorin and to alpha glycophorin CNBr carboxyl terminal fragment C (residues 82–131) and M and N specific monoclonal antibodies (MoAbs) were used. The first two reagents detect specific regions of the alpha glycophorin molecule and all electrophoretically resolved species of glycophorins immunologically related to alpha and delta glycophorins (delta glycophorin, [alpha-delta] hybrids and other glycophorins with an alteration in the carboxyl terminal segment); the M and N MoAbs identified the glycophorin species containing or lacking the M or N determinant in the amino terminal octapeptide structures. We find that immunoblotting confirmed in all cases the serologically determined phenotype; we also find that polymorphic forms of the glycophorin system are relatively infrequent; immunoblotting, independent from serologic testing, was capable of detecting five mutants, two most likely S-s-U-phenotypes; a new glycophorin species was detected in normal red cells with both antiglycophorin and antipeptide C sera, which is not evident with MoAbs; immunoblots of known glycophorin variants (En(a-), U-, Mg, Mi I, II, III, V, and Sta) confirmed but also extended our knowledge of the abnormal glycophorins involved; and the He+ and Wrb(-) cells showed normal patterns.

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42

Nagain, C., M. Rodriguez, J. Martinez, and C. Rozé. "In vivo activities of peptide and pseudo-peptide analogs of the C-terminal octapeptide of cholecystokinin on pancreatic secretion in the rat." Peptides 8, no. 6 (1987): 1023–28. http://dx.doi.org/10.1016/0196-9781(87)90131-8.

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Ueda, Kenji, Ken-Ichi Oinuma, Go Ikeda, et al. "AmfS, an Extracellular Peptidic Morphogen in Streptomyces griseus." Journal of Bacteriology 184, no. 5 (2002): 1488–92. http://dx.doi.org/10.1128/jb.184.5.1488-1492.2002.

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ABSTRACT The amf gene cluster was previously identified as a regulator for the onset of aerial-mycelium formation in Streptomyces griseus. The nucleotide sequences of amf and its counterparts in other species revealed a conserved gene organization consisting of five open reading frames. A nonsense mutation in amfS, encoding a 43-amino-acid peptide, caused significant blocking of aerial-mycelium formation and streptomycin production, suggesting its role as a regulatory molecule. Extracellular-complementation tests for the aerial-mycelium-deficient phenotype of the amfS mutant demonstrated that AmfS was secreted by the wild-type strain. A null mutation in amfBA, encoding HlyB-like membrane translocators, abolished the extracellular AmfS activity without affecting the wild-type morphology, which suggests that AmfBA is involved not in production but in export of AmfS. A synthetic C-terminal octapeptide partially induced aerial-mycelium formation in the amfS mutant, which suggests that an AmfS derivative, but not AmfS itself, serves as an extracellular morphogen.

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44

Maton, P. N., V. E. Sutliff, R. T. Jensen, and J. D. Gardner. "Carbobenzoxy amino acids: structural requirements for cholecystokinin receptor antagonist activity." American Journal of Physiology-Gastrointestinal and Liver Physiology 248, no. 4 (1985): G479—G484. http://dx.doi.org/10.1152/ajpgi.1985.248.4.g479.

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We used dispersed acini prepared from guinea pig pancreas to examine 28 carbobenzoxy (CBZ) amino acids for their abilities to function as cholecystokinin receptor antagonists. All amino acid derivatives tested, except for CBZ-alanine, CBZ-glycine, and N alpha-CBZ-lysine, were able to inhibit the stimulation of amylase secretion caused by the C-terminal octapeptide of cholecystokinin. In general, there was a good correlation between the ability of a carbobenzoxy amino acid to inhibit stimulated amylase secretion and the ability of the amino acid derivative to inhibit binding of 125I-cholecystokinin. The inhibition of cholecystokinin-stimulated amylase secretion was competitive, fully reversible, and specific for those secretagogues that interact with the cholecystokinin receptor. The potencies with which the various carbobenzoxy amino acids inhibited the action of cholecystokinin varied 100-fold and CBZ-cystine was the most potent cholecystokinin receptor antagonist. This variation in potency was primarily but not exclusively a function of the hydrophobicity of the amino acid side chain.

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45

Otsuki, M., Y. Okabayashi, A. Ohki, et al. "Effect of Bt2cGMP on action of cholecystokinin in isolated perfused rat pancreas." American Journal of Physiology-Gastrointestinal and Liver Physiology 251, no. 3 (1986): G293—G299. http://dx.doi.org/10.1152/ajpgi.1986.251.3.g293.

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We have examined the effects of Bt2cGMP on cholecystokinin stimulation of pancreatic exocrine secretion in the isolated perfused rat pancreas. Bt2cGMP produced a concentration-dependent inhibition of the stimulatory effects of cholecystokinin octapeptide (CCK-8, 100 pM) on both pancreatic juice flow and enzyme secretion. Adding 1 mM Bt2cGMP rapidly and completely abolished CCK-8-stimulated pancreatic juice and enzyme secretion. Adding 500 microM Bt2cGMP for 10 min at the termination of 1 nM of CCK-8 infusion caused an immediate and persistent inhibition of the residual response. In contrast, treatment with C-terminal CCK antiserum I had no influence on the residual response. To account for the ability of Bt2cGMP to function as a competitive antagonist of the action of CCK and the ability of the nucleotide to inhibit the residual stimulation caused by CCK, we feel that Bt2cGMP hindered the binding of CCK not only by reducing the association rate constant for hormone binding but also accelerating the dissociation rate.

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46

Indig, F. E., M. Pecht, N. Trainin, Y. Burstein та S. Blumberg. "Hydrolysis of thymic humoral factor γ2 by neutral endopeptidase (EC 3.4.24.11)". Biochemical Journal 278, № 3 (1991): 891–94. http://dx.doi.org/10.1042/bj2780891.

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A search for the natural substrates for neutral endopeptidase (NEP; EC 3.4.24.11) in the immune system led to investigation of the enzyme's action on thymic humoral factor gamma 2 (THF). The ectoenzyme rapidly and efficiently hydrolyses the Lys6-Phe7 bond of the octapeptide. The site of cleavage was confirmed by h.p.l.c. analysis, amino acid analysis and sequence determination of the products. Phosphoramidon (3.6 microM), a potent inhibitor of the enzyme, prevents this cleavage even during prolonged incubation. The high efficiency of hydrolysis of THF by NEP is similar to that reported for [Leu5]enkephalin, and the dipeptide Phe-Leu is the C-terminal product in the hydrolysis of both peptides. The presence of NEP, reportedly identified as the common acute lymphoblastic leukaemia antigen (CALLA), in bone-marrow cells and other cells of the immune system raises the possibility that it may play a role in modulating the activity of peptides such as THF.

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47

Carone, F. A., E. I. Christensen, and G. Flouret. "Degradation and transport of AVP by proximal tubule." American Journal of Physiology-Renal Physiology 253, no. 6 (1987): F1120—F1128. http://dx.doi.org/10.1152/ajprenal.1987.253.6.f1120.

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High-performance liquid chromatography (HPLC) analysis revealed that [3,4,5-3H-Phe3,Arg8]vasopressin ([3H]AVP) was not degraded by isolated renal brush-border membranes or by a cortical lysosomal fraction in vitro; however, in the presence of 1 mM reduced glutathione, [3H]AVP was degraded by both preparations. Renal cortical homogenates in vitro and luminal peptidases of proximal tubule in vivo degraded [3H]AVP and in both instances yielded phenylalanine, hexapeptide AVP 1-6, heptapeptide AVP 1-7, octapeptide AVP 1-8, and two uncharacterized products X and Y. These data suggest that filtered AVP is reduced in the proximal tubule by a reduced glutathione-dependent transhydrogenase and subsequently cleaved to [3H]Phe by tubular aminopeptidases. Following microinfusion of [3H]AVP into proximal tubules, 15.7% of the label was absorbed. Five and fifteen minutes after infusion of [3H]AVP, sequestration of total label in proximal tubules was 4.5 and 2.1%, respectively, and quantitative electron microscope autoradiography revealed accumulation of grains over apical endocytic vacuoles and lysosomes consistent with endocytic uptake and rapid lysosomal degradation of AVP and/or a large metabolite. Thus, enzymatic cleavage of AVP by luminal and lysosomal peptidases in proximal tubules could involve disulfide bond, C-terminal, and N-terminal loci.

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48

Cunnick, J., M. Rider, L. J. Takemoto, and D. J. Takemoto. "Rod/cone dysplasia in Irish setters. Presence of an altered rhodopsin." Biochemical Journal 250, no. 2 (1988): 335–41. http://dx.doi.org/10.1042/bj2500335.

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On the basis of the amino acid sequence of bovine rhodopsin, a series of peptides from the C-terminus (Rhod-4 and Rhod-1) and external loops (Rhod-10) were synthesized. Rabbit antisera to these peptides recognize the rhodopsin molecule in whole retina from 8-week-old normal and affected rcdl (rod/cone-dysplasic) Irish setters (8- and 4-weeks-old). When the rhodopsin content was equalized by using a solid-phase radioimmunoassay, the reaction with anti-peptide antisera to the C-terminal octapeptide (residues 341-348) is severely decreased in the rcdl-dog retinas. The results of mixing experiments suggest that this is not due to proteolytic clipping of the rhodopsin C-terminus from the affected dogs. Treatment of retinas with 1.0 mM-NaF, a phosphatase inhibitor, or pretreatment with alkaline and acid phosphatases does alter the reaction of the rhodopsin with anti-rhodopsin antisera. This suggests that the decreased reaction of the affected rhodopsin with the anti-peptide antisera may partially result from differences in intrinsic rhodopsin phosphorylation. However, since the reaction of rcdl retinas cannot be restored to that of the normals, these results suggest that the rhodopsin molecule from the rcdl dogs may be structurally altered in other ways.

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Laporte, Stéphane A., Antony A. Boucard, Guy Servant, Gaétan Guillemette, Richard Leduc, and Emanuel Escher. "Determination of Peptide Contact Points in the Human Angiotensin II Type I Receptor (AT1) with Photosensitive Analogs of Angiotensin II." Molecular Endocrinology 13, no. 4 (1999): 578–86. http://dx.doi.org/10.1210/mend.13.4.0270.

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Abstract To identify ligand-binding domains of Angiotensin II (AngII) type 1 receptor (AT1), two different radiolabeled photoreactive AngII analogs were prepared by replacing either the first or the last amino acid of the octapeptide by p-benzoyl-l-phenylalanine (Bpa). High yield, specific labeling of the AT1 receptor was obtained with the 125I-[Sar1,Bpa8]AngII analog. Digestion of the covalent 125I-[Sar1,Bpa8]AngII-AT1 complex with V8 protease generated two major fragments of 15.8 kDa and 17.8 kDa, as determined by SDS-PAGE. Treatment of the[ Sar1,Bpa8]AngII-AT1 complex with cyanogen bromide produced a major fragment of 7.5 kDa which, upon further digestion with endoproteinase Lys-C, generated a fragment of 3.6 kDa. Since the 7.5-kDa fragment was sensitive to hydrolysis by 2-nitro-5-thiocyanobenzoic acid, we circumscribed the labeling site of 125I-[Sar1,Bpa8]AngII within amino acids 285 and 295 of the AT1 receptor. When the AT1 receptor was photolabeled with 125I-[Bpa1]AngII, a poor incorporation yield was obtained. Cleavage of the labeled receptor with endoproteinase Lys-C produced a glycopeptide of 31 kDa, which upon deglycosylation showed an apparent molecular mass of 7.5 kDa, delimiting the labeling site of 125I-[Bpa1]AngII within amino acids 147 and 199 of the AT1 receptor. CNBr digestion of the hAT1 I165M mutant receptor narrowed down the labeling site to the fragment 166–199. Taken together, these results indicate that the seventh transmembrane domain of the AT1 receptor interacts strongly with the C-terminal amino acid of[ Sar1, Bpa8]AngII, whereas the N-terminal amino acid of[ Bpa1]AngII interacts with the second extracellular loop of the AT1 receptor.

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Blanchard, David J., Muzaffer Cicek, Jialun Chen та Asim Esen. "Identification of β-Glucosidase Aggregating Factor (BGAF) and Mapping of BGAF Binding Regions on Maize β-Glucosidase". Journal of Biological Chemistry 276, № 15 (2000): 11895–901. http://dx.doi.org/10.1074/jbc.m008872200.

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In certain maize genotypes (nulls), β-glucosidase does not enter the gel and therefore cannot be detected on zymograms. Such genotypes were initially thought to be homozygous for a null allele at theglu1gene. We have shown that a β-glucosidase aggregating factor (BGAF) is responsible for the null phenotype, and it specifically interacts with maize β-glucosidases and forms large insoluble aggregates. To understand the mechanism of the β-glucosidase-BGAF interaction, we constructed chimeric enzymes by domain swapping between the maize β-glucosidase isozymes Glu1 and Gu2, to which BGAF binds, and the sorghum β-glucosidase (dhurrinase) isozyme Dhr1, to which BGAF does not bind. The results of binding assays with 12 different chimeric enzymes showed that an N-terminal region (Glu50-Val145) and an extreme C-terminal region (Phe466-Ala512) together form the BGAF binding site on the enzyme surface. In addition, we purified BGAF, determined its N-terminal sequence, amplified the BGAF cDNA by reverse transcriptase-polymerase chain reaction, expressed it inEscherichia coli, and showed that it encodes a protein whose binding and immunological properties are identical to the native BGAF isolated from maize tissues. A data base search revealed that BGAF is a member of the jasmonite-induced protein family. Interestingly, the deduced BGAF sequence contained an octapeptide sequence (G(P/R)WGGSGG) repeated twice. Each of these repeat units is postulated to be involved in forming a site for binding to maize β-glucosidases and thus provides a plausible explanation for the divalent function of BGAF predicted from binding assays.

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Journal articles on the topic 'Octapeptide c terminal'

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