Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.11 (AMPK)
 12,425 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ribosomal protein S6 was phosphorylated in vitro by the cAMP-independent protein kinase, protease-activated kinase II. The enzyme incorporated up to four phosphates into S6 as shown by analysis of the phosphorylated derivatives by two-dimensional gel electrophoresis. When tryptic digests of S6 phosphorylated by the enzyme were examined by two-dimensional peptide mapping, five phosphopeptides were observed. In contrast, only two phosphopeptides were identified with the cAMP-dependent protein kinase. One phosphopeptide was common to both peptide maps; the others were unique for each enzyme. The physiological significance of the phosphorylation by protease-activated kinase II was verified with phosphopeptide maps of S6 phosphorylated in intact cells. Highly phosphorylated forms of S6 were obtained in rabbit reticulocytes incubated in slightly acidified medium (pH 7.2 to 6.8). The phosphopeptide pattern contained the same five phosphopeptides observed with protease-activated kinase II in vitro indicating the pH-dependent phosphorylation of S6 was mediated by protease-activated kinase II.
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PMID:Protease-activated kinase II mediates multiple phosphorylation of ribosomal protein S6 in reticulocytes. 664 63

Ribosomal protein S6 (rpS6) is phosphorylated in vivo by isoforms of p70 S6 protein kinase and p90 ribosomal S6 kinase, and there is good evidence that it plays a positive role in controlling pancreatic beta-cell size and function. In this report, we demonstrate in the pancreatic beta-cell line MIN6 (mouse insulinoma cell line 6) and islets of Langerhans that agents which stimulate increases in cAMP, such as glucagon-like peptide-1 and forskolin, lead to the phosphorylation of rpS6 at Ser235/Ser236 independently of the activation of the currently known in vivo rpS6 kinases via a pathway that is sensitive to inhibitors of cAMP-dependent protein kinase [protein kinase A (PKA)]. This cAMP-dependent rpS6 kinase activity is also sensitive to PKI in vitro, and PKA exclusively phosphorylates recombinant rpS6 on Ser235/Ser236 in vitro. With these data taken together, we conclude that PKA can phosphorylate rpS6 exclusively at Ser235/Ser236 in vivo in pancreatic beta-cells, thus providing a potentially important link between cAMP signalling and the regulation of protein synthesis. Lastly, we provide evidence that PKA is also likely to phosphorylate rpS6 on Ser235/Ser236 in vivo in a number of other mammalian cell types.
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PMID:Identification of cAMP-dependent kinase as a third in vivo ribosomal protein S6 kinase in pancreatic beta-cells. 1937 32