Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01275 (glucagon)
 26,492 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The specificity of thermomycolase toward glucagon and the oxidized A and B chains of insulin was investigated. Extensive digestion of glucagon occurred when conducted at pH 7.0 and 45 degrees C for 40 min, whereas hydrolysis of only three peptide bonds occurred at pH 7.0 and 28 degrees C for 5 min. A similar situation was observed for the oxidized B chain of insulin, which exhibited only a single major cleavage after 5 min at 25 degrees C. No well-defined specificity for particular amino acid residues was evident, but ready hydrolysis of peptide bonds occurred within sequences containing non-polar residues. This endoproteinase must therefore possess an extended hydrophobic binding site for polypeptides. Thermomycolase hydrolysed acetylalanylalanylalanine methyl ester and elastin-Congo Red at 22 and 8.5 times the rate of porcine elastase respectively. A limited degradation of native collagen and significant hydrolysis of benzyloxycarbonyl-Gly-Pro-Leu-Gly-Pro were suggestive of some collagenase-like activity. No keratinase activity was apparent.
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PMID:The substrate specificity of thermomycolase, an extracellular serine proteinase from the thermophilic fungus Malbranchea pulchella var. sulfurea. 0 73

A fragment of glucagon encompassing its first six NH2-terminal residues (His-Ser-Gln-Gly-Thr-Phe) binds to the glucagon receptor and stimulates adenylate cyclase activity in rat liver plasma membranes. Glucagon1-6 is a partial agonist since it stimulates, at saturating concentrations, to the extent of 75% of the maximal activity given by the native hormone. The binding affinity and potency of glucagon1-6 are 0.001% the native hormone. Discussed are the implications of these findings on the structure-function relationships required for the action of glucagon and for preparing clinically useful analogs of the hormone.
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PMID:Glucagon1-6 binds to the glucagon receptor and activates hepatic adenylate cyclase. 21 70

The actions of insulin and glucagon in the fetal lamb and regulation of their secretion from the fetal pancreas have been examined to assess the possible roles of these hormones in regulating glucose homeostasis in the lamb during fetal life. Much evidence indicates that insulin stimulated glucose utilization in the fetal lamb and that glucagon can promote mobilization of fetal liver glycogen. Glucose stimulates and adrenaline inhibits insulin secretion by fetal pancrease pieces in vitro from 50 days gestation onwards, but alanine and glycine have little effect on insulin release. Alanine and glycine stimulate glucagon secretion by fetal pancreas pieces in vitro from 50 days gestation. The effects are potentiated by caffeine. Adrenaline has a small stimulatory effect but glucagon release is not altered by glucose. In vivo adrenaline infusion increases fetal plasma glucagon concentrations but glycine infusion does not. Glycine infusion into post-natal lambs increases plasma glucagon. Fasting pregnant ewes for two days decreases plasma insulin but does not alter plasma glucagon in either ewe or fetus. The observations suggest insulin secretion in the fetal lamb is an important determinant of glucose uptake and utilization by the fetus during at least the last third of pregnancy. The quantitative importance of glucagon in regulating fetal hepatic glucose metabolism remains uncertain.
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PMID:Glucagon, insulin and glucose homeostasis in the fetal lamb. 61 10

A rise in glomerular filtration rate (GFR) during saline infusion increases outer medullary more than cortical metabolic rate. To determine whether other GFR-increasing agents have a similar effect, renal metabolic rates were estimated by the heat-production technique during infusion of glycine or glucagon. Glycine and glucagon increased GFR by 17 +/- 2 and 32 +/- 2%, renal blood flow (RBF) by 34 and 21%, and outer medullary metabolic rate by 42 +/- 3 and 59 +/- 4%, respectively. Cortical metabolic rate rose by 7 +/- 1% during glucagon, and it increased by 29 +/- 2% during glycine infusion, suggesting a stimulation unrelated to sodium reabsorption. To determine whether glucagon influenced renal metabolism independent of its GFR-increasing effects, vasodilation was achieved by ureteral or suprarenal aortic constriction. Glucagon was without effect on RBF, GFR, and metabolic rate, but infusion of acetylcholine still raised RBF. We conclude that glucagon increases GFR by dilating vascular segments participating in autoregulation, and that energy-requiring NaCl reabsorption in the outer medulla is increased secondary to increased delivery of NaCl.
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PMID:Effect of glycine and glucagon on glomerular filtration and renal metabolic rates. 87 23

Trypsin and elastase isolated from the pancreas of the moose (Alces alces), a member of the Cervidae (deer) family, were characterized with respect to their amino acid composition and specificity towards polypeptides. Moose trypsin possessed 234 residues, based on alanine recoveries equal to 16.0 residues, with a molecular weight calculated at 24 476. Moose trypsin readily hydrolysed peptide bonds in which the carbonyl group was contributed by arginine, lysine and S-2-aminoethylcysteine as indicated by the peptides isolated following hydrolysis of the oxidized and the S-aminoethylated B-chain of insulin. Moose elastase possessed 231 residues, based on alanine recoveries equal to 17.0 residues, with a molecular weight calculated as 24 201. The high lysine (9 residues), low arginine (3 residues) content was in contrast to the opposite situation with porcine elastase and the elastase-like, alpha-lytic protease from Sorangium. The hydrolysis of the oxidized B-chain of insulin by moose elastase was similar to that produced by porcine elastase with major cleavages occurring at Val-12-Glu-13, Ala-14-Leu-15 and Val-18-Cys(O-3H)-19 and minor cleavages occurring at Ser-9-His-10 and Arg-21-Gly-22. The hydrolysis of glucagon with moose elastase produced major cleavages at Thr-7-Ser-8, Ser-11-Lys-12, Val-23-Gln-24 and Leu-26-Met-27. The facile hydrolysis of Arg-17-Arg-18 was also observed and attributed, in part, to trypsin.
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PMID:Characterization of trypsin and elastase from the moose (Alces alces). I. Amino acid composition and specificity towards polypeptides. 112 77

A growth hormone-releasing factor (GRF)-like peptide was isolated from the hypothalamus of common carp, Cyprinus carpio, by acid extraction, gel filtration chromatography, immunoaffinity chromatography using antiserum directed against rat GRF, and multiple steps of HPLC using octadecyl columns. Based on Edman degradation and peptide mapping, this teleost GRF was established to be a 45-residue peptide with the following primary structure: His-Ala-Asp-Gly-Met-Phe-Asn-Lys-Ala-Tyr-Arg-Lys-Ala-Leu-Gly-Gln-Leu-Ser- Ala-Arg - Lys-Tyr-Leu-His-Thr-Leu-Met-Ala-Lys-Arg-Val-Gly-Gly-Gly-Ser-Met-Ile-Glu- Asp-Asp-Asn-Glu-Pro-Leu-Ser. Carp GRF is closely related structurally to peptides of the glucagon-secretin superfamily, and more particularly to mammalian vasoactive intestinal peptide (VIP) precursors and the N-terminal portion of mammalian GRFs. A synthetic replicate of this peptide is highly potent [50% effective dose (ED50) approximately 0.08 nM] in stimulating GH release from cultured goldfish pituitary glands and in elevating serum GH levels 30 min after injection (0.1 micrograms/g) in goldfish.
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PMID:Isolation and characterization of hypothalamic growth-hormone releasing factor from common carp, Cyprinus carpio. 147 12

An amino-terminal histidyl structure (His1) is characteristic of most peptides in the glucagon superfamily. An assay for His1 peptides performed by amino-terminal amino acid sequencing was used to screen venom from the Gila monster lizard, Heloderma horridum. Two His1 peptides were identified: helospectin and a new His1 peptide that has been named exendin-3 to indicate that it is the third peptide to be found in an exocrine secretion of Heloderma lizards which has endocrine activity, the first two being helospectin (exendin-1) and helodermin (exendin-2). In the lot of H. horridum venom tested, exendin-3 was 5-10-fold more abundant in molar concentration than helospectin. The structure of exendin-3 was analyzed by amino acid sequencing and mass spectrometry. Exendin-3 is a 39-amino acid peptide with a mass of 4200. It contains a carboxyl-terminal amide and has a strong homology with secretin at its amino-terminal 12 amino acids. The complete structure of exendin-3 is His-Ser-Asp-Gly-Thr-Phe-Thr-Ser-Asp-Leu-Ser-Lys-Gln-Met-Glu-Glu-Glu-Ala- Val-Arg - Leu-Phe-Ile-Glu-Trp-Leu-Lys-Asn-Gly-Gly-Pro-Ser-Ser-Gly-Ala-Pro-Pro-Pro- Ser- amide. It is 32 and 26% homologous with helospectin and helodermin, respectively. It has greatest homology with glucagon (48%) and human glucagon-like peptide-1 (50%). Exendin-3 (3 microM) stimulated increases in cellular cAMP and amylase release from dispersed guinea pig pancreatic acini.
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PMID:Purification and structure of exendin-3, a new pancreatic secretagogue isolated from Heloderma horridum venom. 170 Jul 85

The effects of synthetic peptides, representing different parts of the secretin molecule in isolated mouse pancreatic islets have been investigated in perifusion studies. In the presence of 10 mM D-glucose the C-terminal nonapeptide Leu-Gln-Arg-Leu-Leu-Gln-Gly-Leu-Val-NH2 (S19-27) showed a 2-fold higher activity than that earlier shown for S22-27 and had the same effect on the dynamic pattern of insulin release as secretin, while the elongating sequence Leu-Gln-Arg (S19-21) had no effect on the insulin release. The nonapeptide Leu-Ser-Arg-Leu-Arg-Asp-Ser-Ala-Arg (S10-18) had no influence on the insulin release. Glucagon release seen after intact secretin could not be shown for any of the smaller fragments. Accumulation of cAMP in the islets as seen with secretin, could at 10 mmol/L D-glucose only be demonstrated with S22-27 or S19-27 but not with S10-18 or S1-6. Our results indicate that full size secretin has to be present to stimulate glucagon release while insulin-releasing activity can be confined to the C-terminal part of the hormone.
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PMID:Differential effects of secretin-fragments imply a dual mechanism of action for secretin. 185 Mar 89

The characteristics of somatostatin (SRIF) receptors in rat pancreatic beta-cells were investigated using rat islets and the beta-cell line HIT-T15 (HIT). The biochemical properties of the SRIF receptors were examined with 125I-labeled des-Ala-1,Gly-2-desamino-Cys-3-[Tyr-11]- dicarba3,14-somatostatin (CGP 23996). 125I-CGP 23996 bound to SRIF receptors in HIT cells with high affinity and in a saturable manner. The binding of 125I-CGP 23996 to SRIF receptors was blocked by SRIF analogues with a rank order of potency of somatostatin 28 (SRIF-28) greater than D-Trp-8-somatostatin greater than somatostatin 14 (SRIF-14). To investigate the physical properties of the HIT cell SRIF receptor, the receptor was covalently labeled with 125I-CGP 23996 using photo-cross-linking techniques. 125I-CGP 23996 specifically labeled a protein of 55 kDa in HIT cell membranes. The size of the SRIF receptor in HIT cells is similar to the size of the SRIF receptor labeled with 125I-CGP 23996 in membranes of freshly isolated islets, suggesting that the physical properties of SRIF receptors in HIT cells and rat islet cells are similar. The binding studies suggest that beta-cells predominantly express a SRIF-28-preferring receptor. In freshly isolated islets, glucose- and arginine-stimulated insulin release was effectively blocked by SRIF-28 but not by SRIF-14. SRIF-14 did inhibit arginine-stimulated glucagon secretion from freshly isolated islets. The dissociation of the inhibitory effects of SRIF-28 and SRIF-14 on insulin and glucagon release from freshly isolated islets suggests that the two peptides act through different receptors in islets to regulate hormone secretion.
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PMID:Pancreatic beta-cell somatostatin receptors. 197 86

Brain natriuretic peptide (BNP) is a recently discovered family of natriuretic peptides highly homologous to atrial natriuretic factor (ANF). Quantitative in vitro autoradiography with a computerized microdensitometer demonstrated that the distribution of BNP binding sites is similar to the known distribution pattern of ANF binding sites in rat tissues. Analysis of saturation and competition curves disclosed that the maximal binding capacity for BNP-(Asp-81--Tyr-106) and ANF-(Ser-99--Tyr-126) is similar within the plexiform layer of the olfactory bulb, the choroid plexus, and the adrenal zona glomerulosa. Examination of the competition curves of BNP-(Asp-81--Tyr-106), ANF-(Ser-99--Tyr-126), and des-(Gln-116--Gly-120)ANF-(Asp-102--Cys-121)NH2 (C-ANF, a ligand highly specific for ANF-R2 receptors) for 125I-labeled BNP-(Asp-81--Tyr-106) and 125I-labeled ANF-(Ser-99--Tyr-126) binding revealed that ANF fully displaced 125I-BNP binding and, conversely, BNP completely displaced 125I-ANF binding in these tissues, whereas C-ANF partially displaced 125-BNP and 125-ANF binding. Angiotensin II, insulin, glucagon, and substance P had no influence on 125I-BNP binding in the above tissues. These results support the view that BNP and ANF share the same binding sites in rats.
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PMID:Brain natriuretic peptide binding sites in rats: in vitro autoradiographic study. 216 36


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