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)

1. Studies were performed to investigate the metabolic fate of dipeptides when administered intravenously in rats. Glycyl-leucine, glycylglycine or glycylsarcosine was injected into the jugular vein. The plasma disappearance rate after the peak plasma concentrations was most rapid for glycyl-leucine and least rapid for glycylsarcosine. 2. During urine collection for 40 min, trace amounts of glycyl-leucine and glycylglycine and 13% of the injected glycylsarcosine were excreted. 3. Neither glycylglycine nor glycyl-leucine was detected in the liver, muscle, intestinal mucosa or renal cortex, but concentrations of glycine or leucine, or both, in these tissues were increased after each injection. In contrast, glycylsarcosine was recovered in all these tissues with concentrations in the renal cortex being far greater than in any other tissue, but sarcosine was found only in the renal cortex and intestinal mucosa. 4. The changes in plasma concentrations of free amino acids, glucose and glucagon, and tissue concentrations of free amino acids, were similar after the intravenous administration of glycyl-leucine and an equimolar mixture of free glycine and leucine. However, the amount of insulin secreted during the 40 min after glycyl-leucine injection was 1-6 times that produced after the injection of the corresponding amino acid mixture. 5. Results show that, within the present experimental conditions, the intravenous administration of dipeptides is as effective as that of the corresponding free amino acids in enriching the tissue pools of amino acids. It is suggested that efficient hydrolysis by cellular enzymes prohibits accumulation of intact dipeptides in body tissues.
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PMID:Metabolism of intravenously administered dipeptides in rats: effects on amino acid pools, glucose concentration and insulin and glucagon secretion. 40 46

A manual high-sensitivity sequencing method is described, in which 4-NN-dimethylaminoazobenzene 4'-isothiocyanate is used for the stepwise degradation of amino acid residues from the peptides. The 4-NN-dimethylaminoazobenzene 4'-thiazolinones of amino acids that were released, after conversion into their thiohydantoin derivatives, were identified by t.l.c. on polyamide sheets. This new method is simple and sensitive, and requires only 2-10nmol of peptides or proteins for extended sequence analysis. The method was tested on the sequence analysis of a hexapeptide (Leu-Trp-Met-Arg-Phe-Ala), bradykinin, glucagon and native lysozyme. Results show that the proposed procedure is a sensitive method for the sequence determination of short peptides as well as for the partial sequence determination of intact proteins.
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PMID:High-sensitivity sequence analysis of peptides and proteins by 4-NN-dimethylaminoazobenzene 4'-isothiocyanate. 40

The 7- to 10-fold increase in the rat liver serine:pyruvate aminotransferase activity after glucagon administration was shown to occur mainly in the mitochondrial matrix of parenchymal cells. The enzyme was purified from glucagon-treated rat liver mitochondria to apparent homogeneity as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A specific rabbit antibody was prepared against the purified enzyme. Upon Ouchterlony double diffusion analysis, the mitochondrial extracts of glucagon-treated rat liver produced a single and fused precipitin line between the purified enzyme against the antibody. The supernatant fraction of glucagon-treated rat liver and the mitochondrial extracts of normal liver were also shown to make a single and fused precipitin line with the purified enzyme, when applied in large quantities. The quantitative immunotitration demonstrated that the glucagon-induced increase in the activity of liver serine:pyruvate aminotransferase were accompanied by the parallel increase in the amount of the enzyme antigen. Isotopic leucine incorporation studies showed that the relative rate of synthesis of the enzyme was increased approximately 10-fold by glucagon administration under the conditions employed. The rate of the degradation of the aminotransferase in the normal rat liver was a relatively slow process with a half-life of approximately 30 h. Thus the accumulation of serine:pyruvate aminotransferase in rat liver mitochondria by glucagon treatment can be ascribed mainly to the rise in the rate of enzyme synthesis.
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PMID:Immunochemical studies on induction of rat liver mitochondrial serine: pyruvate aminotransferase by glucagon. 41 59

In ten patients with a femoral shaft fracture, arterial plasma amino acids and glucagon, blood glucose, and serum insulin were measured after an overnight fast on the third, fifth, and seventh days following injury. Ten normal subjects were controls. On all days, concentrations of the key glucogenic amino acid, alanine, were the same in both groups, but levels of another glucogenic amino acid, glycine, were significantly less in the fracture patients. Other amino acid changes following injury were maximal at 7 days, with significant elevations of phenylalanine, methionine, tyrosine, ornithine, lysine, arginine, valine, isoleucine, and leucine. Increased levels of insulin, glucose, valine, isoleucine, and leucine on the fifth and seventh days after injury implied insulin resistance. Plasma glucagon was elevated on the third (p less than 0.05) and seventh (p less than 0.01) days after injury, but the concentrations measured are insufficient to explain the impaired carbohydrate tolerance following a fracture.
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PMID:Arterial plasma amino acids during the first week following femoral shaft fracture. 43 79

The direct in vitro effect of caerulein on pancreatic protein synthesis and amino acid transport has been investigated. In contrast to in vivo conditions we were unable to demonstrate any effect on alpha-aminoisobutyric acid and leucine uptake and on leucine incorporation usin rat pancreatic lobules. Insulin and glucagon were therefore examined as possible mediators for the in vivo effect of caerulein. Insulin (1--5 microM) slightly enhanced AIB uptake (16% but did not change uptake and incorporation of leucine. Glucagon (0.01--1 microM) was ineffective. Both islet hormones had no influence on the formation of cyclic GMP induced by secretagogue either in rat (40% increase) or in guinea pig lobules (500% increase). It seems unlikely that the two islet hormones exert any direct effect on the exocrine pancreas and thus could serve as mediators for the in vivo synthetic effect of caerulein.
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PMID:Amino acid transport in the exocrine pancreas. IV. Do glucagon or insulin mediate the in vivo effect of caerulein on amino acid transport and incorporation? 47 31

Serum-free media containing 10-50 ng insulin, glucagon and epidermal growth factor (EGF) ml-1 stimulate adult rat hepatocyte proliferation in 10-15 day old primary liver cell cultures. The kinetics of this response simulate hepatocellular transitions that accompnay liver regeneration after 67% hepatectomy. Amiloride, a Na+ influx inhibitor, reversibly blocks these transitions in vitro (ID50 approximately 0.02 mM) and in vivo (ID50 approximately 25 mg kg-1). Inhibition is observed with other cation flux modulators, including ouabain (ID50 approximately 0.2 mM), 0.2 microM monensin and 0.2 microM nigericin, but not with 0.3 mM furosemide or tetrodotoxin. The prereplicative interval in culture (0-12 hr) is characterized by preferential cellular responsiveness to EGF (0-3 hr) followed by insulin plus glucagon (3-12 hr). Parallel culture and animal studies show that the amiloride-sensitive and prereplicative intervals coincide. In culture, a "burst" of 22Na+ influx, stimulated by peptide-supplemented media within 1 min but decreased later at 12 hr, is retarded by amiloride. This drug also blocks delayed prereplicative events involving increased amino acid "A" transport system function at 4-8 hr, and 3H-uridine and 3H-leucine incorporation into RNA and protein, respectively, at 8-12 hr. These findings suggest that at least two time-ordered processes are necessary to initiate hepatic growth fully: first, activation of Na+ flux systems by peptides similar or identical to EGF; and second, potentiation of these and subsequent cellular events by the combined action of insulin plus glucagon. [Amiloride: N-amidino-3,5-diamino-6-chloropyrazinecarboxamide; furosemide: 4-chloro-N-furfuryl-5-sulfamoylanthranilic acid; AIB: alpha-aminoisobutyric acid; ID50: administered dose giving 50% inhibition of a maximal response; dFBS: dialyzed fetal bovine serum; L.I.: 3H-dT nuclear labeling index.]
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PMID:Increased sodium ion influx is necessary to initiate rat hepatocyte proliferation. 50 19

Circadian variations in liver protein synthesis were were assessed in control rats fed a mixed 10% protein diet and in rats fed proteins as a separate meal either at 09:00 (SF 09) or at 21:00 (SF 21) and provided with a protein-free diet ad libitum. Protein synthesis was measured by incorporation of labelled leucine over a short period of time (15 min) at time-points regularly spaced over 24 h. In controls, the circadian variations observed were of moderate amplitude (from 2.75 mg/h per g at 09:00 to 5.77 mg/h per g at 06:00) correlated with increased protein and RNA contents of the liver. In separately fed animals ingestion of the protein meal triggered a 300% increase in protein synthesis within 1 h while the feeding pattern was unaltered. In the SF 09 group, high synthetic activity was not followed by an increase of hepatic protein content while hepatic urea concentrations were sharply increased and glucogenic amino acid pools were greatly depleted. It is suggested that the high influx of amino acids consecutive to the absorption of the dietary proteins is the key factor stimulating protein synthesis, while synchronisation with the energetic metabolism controls the degree of degradation. The possible involvement of variations in the insulin to glucagon ratio is discussed.
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PMID:Regulation of hepatic synthesis of proteins by the chronology of protein ingestion. 62 71

An oral phenylalanine load provokes a significant drop in serum tyrosine levels in children with phenylketonuria [8]. The aim of the present investigation was to examine the response of insulin and glucagon to oral phenylalanine loading as these hormones are known to have a hypoaminoacidaemic effect. Six adult normal weight and healthy men were loaded orally with 0.6 mmol L-phenylalanine per kg body weight after an overnight fast. Serum phenylalanine increased within 10 min after the load and reached a maximum concentration at 30 min. Serum tyrosine increased within 10 min after the load and reached a maximum concentration at 2 h. Plasma glucagon and insulin increased during the first 10 min after the load and reached a peak twice the fasting levels at 30 min after the load. The molar insulin/glucagon ratio remained unchanged during the first 20 min after the load but then declined by 50% at 2 h. Associated with this decline plasma amino acid concentration (except phenylalanine and tyrosine) declined by approximately 15%. The decline was most marked for isoleucine, leucine, methionine and valine. As the hypoaminoacidaemic effect of insulin and glucagon is known to be most marked for these four amino acids plus phenylalanine and tyrosine, the response of insulin and glucagon to a phenylalanine load may influence not only the fate of phenylalanine given but also the blood tyrosine level.
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PMID:Effects of oral phenylalanine load on plasma glucagon, insulin, amino acid and glucose concentrations in man. 66 49

1 The relaxant action of glucagon has been studied in strips of rabbit renal arteries partially contracted by a low concentration (1 ng/ml) of noradrenaline.2 The preparation was relaxed in a dose-dependent manner by concentrations of glucagon varying between 25 ng/ml and 420 ng/ml.3 The relaxant effect of glucagon (0.1 mug/ml approximately ED(60)) on this preparation was not affected by propranolol (5.0 mug/ml), cimetidine (10 mug/ml), diphenhydramine (10 mug/ml), indomethacin (5.0 mug/ml), phentolamine (1.2 mug/ml), atropine (10 mug/ml) and 8-Leu-AT(II) (1.0 mug/ml) but was slightly potentiated by Des-Arg(9) Leu-OMe(8)-Bk (25 mug/ml) and indomethacin (50 mug/ml).4 The dose-response curve to glucagon remained parallel in the presence of papaverine (2.5 mug/ml) but was shifted to the left by a factor of 2.5 to 2.8. Theophylline (250 mug/ml) also potentiated the vascular relaxation induced by glucagon.5 Insulin (10 mug/ml) did not influence the relaxant effect of glucagon.6 The removal of the N-terminal amino acid (His) of glucagon reduced by 89% the biological activity of this fragment on the vascular preparation. The removal of the C-terminal amino acids Met-27, Asn-28 and Thr-29 of glucagon resulted in a fragment which was inactive either as an agonist or as an antagonist when tested at concentrations as high as 925 ng/ml.7 It is concluded that the relaxation of partially contracted strips of rabbit renal arteries by glucagon constitutes a simple, sensitive, relatively specific and reliable bioassay which may be useful for the determination of glucagon in biological materials and for structure-activity relationship studies with this hormone.
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PMID:A new bioassay for glucagon. 69 87

The selective cleavage of peptide bonds by a serine protease from skeletal muscle (SK-protease) was examined using glucagon and neurotensin as substrates. Among the peptide bonds cleaved in these substrates, the most susceptible were Phe-Thr-Ser, Tyr-Leu, Trp-Leu, and Tyr-Ile. These results indicate that the SK-protease hydrolyzed the carboxyl side of aromatic amino acid residues under the experimental conditions. When the amino acid on the carboxyl side of aromatic amino acid residues was serine, threonine or glutamic acid, these peptide bonds, such as Phe-Thr, Tyr-Ser, and Tyr-Glu, were not susceptible to another serine protease from small intestine (SI-protease) under the same experimental conditions. The peptide bond between the arginines of Pro-Arg-Arg-Pro in neurotensin was hydrolyzed by the SI-protease, but not by the SK-protease. Thus the specificity of the SK-protease differs from that of the SI-protease. These results suggest that the specificity of the hydrolytic action of the SK-protease is more like that of bovine chymotrypsin A than like that of porcine chymotrypsin C and of the SI-protease.
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PMID:Selective cleavage of peptide bonds by a serine protease from rat skeletal muscle. 70 Dec 36


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