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)

A phosphorylated form of alpha-Gi-2 (the alpha-subunit of Gi-2), immunoprecipitated from hepatocytes under basal conditions, migrated as a single species of pI approximately 5.7, the labelling of which increased approximately 2-fold in cells challenged with either vasopressin or phorbol 12-myristate 13-acetate (PMA); agents which activate protein kinase C. In contrast, treatment of hepatocytes with 8-bromo-cyclic AMP produced a more acidic species of phosphorylated alpha-Gi-2 having a pI of approximately 5.4 and whose labelling was increased approximately 3-fold. Trypsin digestion of labelled alpha-Gi-2 isolated from hepatocytes under basal conditions identified, on two-dimensional peptide analyses, three positively charged phosphoserine-containing peptides (C1, C2 and C3), with only peptides C1 and C2 being evident upon less extensive digestion with trypsin. These are suggested to reflect a single site of phosphorylation, with proteolysis by trypsin being incomplete, and where C2 is larger than C1, which is larger than C3. An identical pattern of tryptic phosphopeptides was seen in hepatocytes treated with either vasopressin or PMA, although labelling of this group of peptides was increased by approximately 2-fold compared with the basal state. In contrast, treatment of hepatocytes with glucagon, 8-bromo-cyclic AMP or forskolin not only resulted in increased labelling of the 'basal' sites approximately 3-fold, but identified a novel positively charged tryptic phosphoserine-containing peptide (AN). All four tryptic peptides were susceptible to proteolysis by V8 protease. Treatment of labelled alpha-Gi-2 from basal and PMA-treated cells produced a pattern of peptides which was identical with those found when the tryptic phosphopeptide was treated with V8 protease. We tentatively suggest that, on alpha-Gi-2, Ser144 is phosphorylated through the action of protein kinase C and Ser207 is phosphorylated upon elevation of the intracellular concentrations of cyclic AMP.
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PMID:Multi-site phosphorylation of the inhibitory guanine nucleotide regulatory protein Gi-2 occurs in intact rat hepatocytes. 805 95

Pancreaticobiliary diversion (PBD) and biliodigestive shunt (BDS) cause long-standing hypercholecystokininemia followed by pancreatic hyperplasia. These changes have been suggested to be due to the lack of intraluminal trypsin and bile, respectively, in the upper small intestine. The aim of these experiments was to study the effect of restoration of intraluminal trypsin and bile on plasma levels of cholecystokinin (CCK) and the changes found in exocrine and endocrine pancreas after PBD and BDS. Male Sprague-Dawley rats were used. PBD was done in 16 rats, eight of which had trypsin dissolved in 50 mM sodium bicarbonate (SB), and eight had SB only by gastric intubation twice daily. BDS was done in another 16 rats, eight of which had bile dissolved in SB, and eight had SB in a similar manner. Sham-operated rats had SB and served as controls. After 4 weeks, the rats were killed, and the concentrations of circulating CCK, gastrin, glucose, glucagon, and insulin were determined. The pancreas was removed, weighed, and analyzed for contents of water, protein, and DNA. In another study, PBD-operated rats got trypsin in varying dosages or trypsin and taurocholate in combination for 2 weeks before death. The concentrations of plasma CCK and glucagon were elevated after both PBD and BDS. PBD decreased the concentration of gastrin in plasma. PBD caused an increase of pancreatic weight and the contents of protein and DNA. Trypsin substitution to PBD-operated rats did not affect plasma CCK or glucagon levels, but the PBD-induced increases in weight and DNA content were counteracted by trypsin. Higher dosages of trypsin did not further influence the effects seen after PBD. Pancreatic weight and DNA content were increased after BDS. Bile administration completely abolished the increase in plasma CCK and glucagon, as well as the gain in pancreatic weight, and reduced the increase in pancreatic DNA. Substitution with bile to BDS-operated rats abolished the increase in the plasma levels of CCK and glucagon, as well as the trophic effects on the pancreas. Trypsin substitution to PBD-operated rats partly reversed the trophic effects on the pancreas but not the hormonal changes in plasma. Thus the trophic effects on the pancreas exerted by BDS seem to be dependent on the lack of bile in the upper small intestine, whereas the effects of PBD only partly are a consequence of the absence of intraluminal trypsin.
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PMID:Effects of intraluminal trypsin and bile on the exocrine and endocrine pancreas after pancreaticobiliary diversion and biliodigestive shunt. 1070 33


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