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 effect of phorbol myristate acetate (PMA) on the hormonal responsiveness of hepatocytes from lean and obese Zucker rats was studied. Phenylephrine-stimulated phosphatydylinositol labeling and phosphorylase activation were antagonized by PMA in cells from obese and lean animals; bigger residual effects were observed in cells from obese animals even at high PMA concentrations. Cyclic AMP accumulation induced by isoproterenol, glucagon, forskolin and cholera toxin was higher in cells from lean animals than in those from obese rats. PMA diminished glucagon- and cholera toxin-induced cyclic AMP accumulation; cells from lean animals were more sensitive to PMA. Two groups of isoforms of protein kinase C (PKC) were observed in hepatocytes from Zucker rats using DEAE-cellulose column chromatography: PKC 1 and PKC 2. The PKC 1 isozymes were separated into four peaks using hydroxylapatite: aa, 1a (PKC-beta), 1b (PKC-alpha) and 1c. Short treatment with PMA decreased the activity of PKC 1 (peaks 1b (PKC-alpha) and 1c) and to a lesser extent of PKC 2; cells from lean animals were more sensitive to PMA than those obtained from obese rats. Our results indicate that cells from genetically obese Zucker rats are in general less sensitive to this activator of protein kinase C than those from their lean littermates. The possibility that alterations in the phosphorylation/dephosphorylation cycles, that control metabolism and hormonal responsiveness, may contribute to this obese state is suggested.
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PMID:Modulation by protein kinase C of the hormonal responsiveness of hepatocytes from lean (Fa/fa?) and obese (fa/fa) Zucker rats. 161 41

An arginine esterase was purified from the venom of Vipera lebetina by gel filtration on Sephadex G-100 and by affinity and DEAE-cellulose chromatography. The enzyme has a mol. wt of 52,500 and pI approximately 3. It is a glycoprotein containing 23% of neutral sugars, and has extremely high thermostability. The esterase activity is inhibited by diisopropylfluorophosphate (DFP) and phenylmethylsulfonyl fluoride (PMSF). The Km and kcat values are for alpha-N-benzoyl-L-arginine ethyl ester (BAEE) 7.7 x 10(-5) M and 43.8 sec-1, for p-tosyl-L-arginine methyl ester (TAME) 3.6 x 10(-4) M and 39.8 sec-1 (pH 8.5, 25 degrees C, and for alpha-N-benzoyl-DL-arginine-4-nitroanilide (BAPNA) 1.8 x 10(-4) M and 0.94 sec-1 (pH 8.3, 25 degrees C), respectively. Lysine esters are not hydrolyzed. The enzyme has weak caseinolytic activity and hydrolyzes glucagon at the sites Lys12-Tyr13, Arg17-Arg18 and Arg18-Ala19. In fibrinogen it cleaves B beta-chain first and later also the A alpha-chain.
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PMID:Beta-fibrinogenase from the venom of Vipera lebetina. 202 69

An enkephalin-binding protein was found in human plasma and serum. The protein was partially purified by DEAE-cellulose column chromatography. The binding of [3H]leucine-enkephalin to this protein was competitively inhibited by unlabeled leucine- and methionine-enkephalin and various peptide hormones such as beta-endorphin and glucagon, but not by Leu-enkephalin-amide. The fact that amide derivatives of leucine-enkephalin and methionine-enkephalin did not inhibit the binding suggests that c-terminuses of enkephalins might have an important part in binding the protein. From these results, physiological roles of the enkephalin-binding protein are discussed.
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PMID:Enkephalin-binding protein in human blood. 281 10

Vasopressin has been shown previously to lower the glucagon-induced increase of cyclic AMP levels in isolated rat hepatocytes by way of an enhanced phosphodiesterase (EC 3.1.4.17) activity. Five phosphodiesterase inhibitors were tested for their ability to prevent vasopressin from lowering cyclic AMP levels in intact hepatocytes and for their inhibitory effect in vitro on soluble and particulate phosphodiesterase activities partially purified from hepatocytes. Three soluble activities have been separated by DEAE-cellulose chromatography: a phosphodiesterase hydrolyzing both cyclic AMP and cyclic GMP, a form stimulated by cyclic GMP and a cyclic AMP-specific activity. The absence of any statistically significant correlation between the in vivo (in intact cells) and the in vitro (on isolated phosphodiesterases) potencies of the inhibitors does not support a role for the cytosolic phosphodiesterases in mediating the vasopressin-induced decrease in cyclic AMP levels. No statistically significant correlation was observed between the inhibition of the vasopressin effect on cyclic AMP accumulation and the inhibition of phosphodiesterase activity either associated with the native plasma membranes or solubilized from these membranes with 0.4 M NaCl. In contrast, a statistically significant correlation was observed between the degree of inhibition of the vasopressin effect in the intact cells and the degree of inhibition of the intrinsic phosphodiesterase still associated with the plasma membranes after high-salt treatment. These data indicate that a phosphodiesterase activity integral to the plasma membrane is very likely involved in the negative control of cyclic AMP levels by vasopressin.
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PMID:Involvement of a plasma membrane phosphodiesterase in the negative control of cyclic AMP levels by vasopressin in rat hepatocytes. 284 89

An insulin-degrading enzyme (IDE) was purified from the cytosol of human erythrocytes via the use of ammonium sulfate precipitation and chromatography on columns composed of DEAE-Sephadex, pentylagarose, hydroxylapatite, chromatofocusing resins, and Ultrogel AcA-34. The final preparation was purified greater than 50,000-fold and exhibited a single protein band of Mr = 110,000 on reduced sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. Cross-linking of 125I-labeled insulin to the enzyme preparation labeled a protein of the same molecular weight, indicating that this band was in fact the enzyme. Intact insulin, insulin B chain, and glucagon inhibited this cross-linking half-maximally at concentrations of 0.1, 1, and 1.5 microM, respectively. Under nondenaturing conditions, the enzyme had an Mr = 300,000, suggesting that the enzyme may exist under physiological conditions as a dimer or timer. The purified enzyme was inhibited by both sulfhydrylmodifying reagents and chelating agents, indicating that a free thiol and metal were both required for the activity of the enzyme. The purified enzyme was found to degrade physiological concentrations of intact insulin more rapidly than insulin B chain, although at high substrate concentrations (greater than 1 microM) the enzyme degraded B chain to a greater extent. Additional characteristics of the enzyme were a pl of 5.2 and a pH optimum of 7.0. These properties of the red blood cell (RBC) enzyme were very similar to those reported for IDEs from other tissues. Moreover, a polyclonal antiserum to the IDE from skeletal muscle was found to recognize the RBC enzyme.
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PMID:Purification and characterization of insulin-degrading enzyme from human erythrocytes. 351 22

Glucagon-like immunoreactivity (GLI) was extracted from porcine ileal mucosa with boiling 2 M HAc followed by elution on DEAE A-50 and fractionation on Sephadex G-50 F. Intact GLI was isolated from mesenteric blood by fractionation of several plasma samples from a mesenteric vein of a dog on Sephadex G-50 M followed by refractionation of the pooled GLI from these columns on G-50 F. Analysis of the semipurified mucosal and plasma GLI on Sephadex G-50 SF, eluted with 0.1 M Tris/HCl + 8 M urea, pH 7.5, demonstrated a single, sharp peak of GLI with a relative molecular mass (Mr) between 12,000 and 13,000. Electrophoresis on PAGE gels at acid pH with 2 M urea demonstrated a single charged GLI species in both the plasma and mucosal fractions. Stimulation of the release of GLI from a loop of ileum isolated in situ in an anesthetized dog followed removal of the known sources of glucagon (stomach, pancreas, and duodenum) resulted in an immediate and sustained increase in hepatic glucose production. The isolated GLI from ileal mucosa (5 X 10(-8) M) stimulated gluconeogenesis from 10 mM [14C]alanine in hepatocytes isolated from fed rats. The stimulation was equal to 25% of the maximal stimulation observed with 10(-8) M glucagon. These experiments demonstrate that the ileum synthesizes and secretes a GLI peptide with a Mr of approximately 12,000 that stimulates hepatic glucose production in vivo and in vitro.
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PMID:Characterization of a heat stable, 12,000 Da, glucagon-like immunoreactive (GLI) peptide from porcine ileum that stimulates hepatic glucose production in vivo and in vitro. 400 Nov 31

When young rats (less than 14 days old) were treated once a day for 2 days with 100 micrograms/100 g body weight of dexamethasone, their liver cytosol showed a sharp new peak of glucocorticoid binding protein (peak C) eluted with 0.14 M NaCl on DEAE-cellulose chromatography. When the young rats were given a single injection of the hormone, the chromatogram showed a dominant peak of binding protein (peak B), eluted with 0.07 M NaCl, which was similar to that in untreated rats. The appearance of peak C on two treatments of young rats with hormone was confirmed by both in vivo and in vitro labeling and also studies on the nuclear fraction. Peaks B and C were specific hormone-binding proteins as shown with excess unlabeled hormone. The appearance of peak C was concomitant with the precocious induction of tryptophan dioxygenase in the liver of the young rats, and pretreatment with two injections of dexamethasone were necessary for maximal enzyme induction. On the other hand, in adult rats a single injection of dexamethasone (of 20 micrograms/100 g body weight or more) was enough to cause the appearance of peak C and induce tryptophan dioxygenase activity maximally; an additional injection of the hormone did not change the chromatographic pattern of the specific binding or the enzyme activity. For this effect in young rats, dexamethasone could not be replaced by other hormones such as glucagon, growth hormone, thyroid hormones, insulin, sex steroids or short-acting glucocorticoid.
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PMID:Precocious induction of tryptophan dioxygenase by glucocorticoid in suckling rats and correlation with change in glucocorticoid receptor. 405 55

1. A neutral peptidase, previously shown to be located in the brush border of the proximal tubule, and assayed by its ability to hydrolyse [(125)I]iodoinsulin B chain was purified from rabbit kidney. 2. The starting material for the purification was a microsomal pellet prepared from a homogenate of cortical tissue. The membrane-bound enzymes were solubilized by treatment with toluene and trypsin. About half the neutral peptidase activity was released by this treatment in a form that no longer sedimented with the microsomal pellet and which penetrated polyacrylamide gels when subjected to disc electrophoresis. Other treatments with detergents or proteolytic enzymes either inactivated the peptidase or failed to convert it into a genuinely soluble form. 3. Chromatography with successive columns of Sephadex G-200, DEAE-cellulose and hydroxyl-apatite yielded an enzyme that was free of other brush-border peptidase activities and which was homogeneous on disc electrophoresis and ultracentrifugation. 4. The purified enzyme attacked [(125)I]iodoglucagon at a rate comparable with that for [(125)I]iodoinsulin B chain. It did not appear to attack proteins (insulin, albumin and casein) that had been similarly iodinated. 5. Unlabelled insulin B chain and unlabelled glucagon were substantially hydrolysed by the endopeptidase, whereas insulin and albumin released only trivial amounts of ninhydrin-reacting material. The resistance of insulin to attack by endopeptidase, even after prolonged incubation, was confirmed by biological and immunoassay. 6. The specificity of the peptidase was determined by analysis of the products after incubating unlabelled insulin B chain, and some oligopeptide substrates, including pentagastrin, with the enzyme. All of the bonds readily cleaved were those involving the alpha-amino group of hydrophobic residues, i.e. x-Leu-, x-Val-, x-Tyr-, x-Phe- and x-Met-, provided that the residues were not C-terminal. 7. The enzyme showed only endopeptidase activity. Substrates suitable for aminopeptidases, carboxypeptidases or esterases were not attacked.
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PMID:The purification and specificity of a neutral endopeptidase from rabbit kidney brush border. 442 92

Using a radioimmunoassay with labeled synthetic tetradecapeptide somatostatin, a large amount of immunoreactive somatostatin was found in the principal pancreatic islet of the channel catfish (Ictalurus punctata). The purpose of these experiments was to isolate and characterize the somatostatin-like material. Extracts of islets were chromatographed on a Bio-Gel P-30 column, and over 90% of the immunoreactive somatostatin migrated with proteins at least twice the size of synthetic tetradecapeptide somatostatin. This fraction was further purified by ion-exchange chromatography on carboxymethyl-cellulose and DEAE-cellulose columns. Two peptides were obtained with identical immunoreactivity, which was approximately 25% that of the synthetic somatostatin. Each peptide was judged to be >95% pure by thin-layer electrophoresis, polyacrylamide gel electrophoresis at pH 8.9, and highpressure liquid chromatography. Further criteria of purity included amino-terminal analysis of fraction IV yielding only aspartic acid. A total of 1.3 mg of fraction II, and 3.8 mg of fraction IV somatostatin-like peptides were obtained from 10 g of fresh frozen islets. Characterization of the two peptides revealed both peptides slightly more acidic than synthetic tetradecapeptide somatostatin. Fraction II had an isoelectric point of 8.0-8.3, and fraction IV 8.3-9.0. Molecular weight estimation by sodium dodecyl sulfate-urea polyacrylamide gel electrophoresis revealed similar mobility of both peptides, between pancreatic polypeptide (mol wt 4,500) and glucagon (mol wt 3,500). The mobility was not altered by reduction, and was approximately twice the size of synthetic tetradecapeptide somatostatin (mol wt 1,800). This confirmed that the peptides were single polypeptide chains and not aggregates, or somatostatin bound to larger proteins. Molecular weight determination by gel filtration chromatography on Bio-Gel P-6 in 8 M urea gave an estimated mol wt of 3,700. Amino acid analysis of the two immunoreactive somatostatins indicated that they were very similar in composition. Both pancreatic somatostatins (1 muM) had full biological activity relative to synthetic somatostatin measured as inhibition of growth hormone release from rat anterior pituitary cells.
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PMID:Isolation and characterization of immunoreactive somatostatin from fish pancreatic islets. 610 73

Addition of glucagon to isolated rat hepatocytes resulted in inhibition of 6-phosphofructo-2-kinase (ATP:D-fructose-6-phosphate-2-phosphotransferase) activity in extracts of the cells and in a decrease in the intracellular level of fructose 2,6-bisphosphate. The effect on 6-phosphofructo-2-kinase was characterized by a decrease in the affinity of the enzyme for fructose 6-phosphate. To investigate the mechanism of action of glucagon, 6-phosphofructo-2-kinase from rat liver was partially purified by polyethylene glycol precipitation, DEAE-cellulose chromatography, (NH4)2SO4 fractionation, Sephacryl S-200 gel filtration, DEAE-Sephadex chromatography, and Sephadex G-100 gel filtration. Incubation of the purified enzyme with the catalytic subunit of the cyclic AMP-dependent protein kinase from rat liver and [gamma-32P]ATP resulted in 32P incorporation into a protein with a subunit Mr of 49,000 as determined by NaDodSO4 disc gel electrophoresis. Associated with this phosphorylation was an inhibition of 6-phosphofructo-2-kinase activity that was also characterized by a decrease in the affinity of the enzyme for fructose-6-phosphate. Both the phosphorylation and the inhibition of the purified 6-phosphofructo-2-kinase were blocked by addition of the heat-stable protein kinase inhibitor. It is concluded that the glucagon-induced decrease in fructose 2,6-bisphosphate levels observed in isolated hepatocytes is due, at least in part, to cyclic AMP-dependent phosphorylation and inhibition of 6-phosphofructo-2-kinase.
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PMID:Regulation of 6-phosphofructo-2-kinase activity by cyclic AMP-dependent phosphorylation. 628 62


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