Insulin secretion and protein phosphorylation in PKC-depleted islets of Langerhans.
Protein kinase C (PKC)-dependent phosphorylation of endogenous substrates was measured in electrically permeabilised rat islets of Langerhans. The PKC-activating phorbol ester, 4 beta-phorbol myristate acetate (PMA), caused a slow but prolonged increase in insulin secretion from permeabilised islets, which was accompanied by increased 32P incorporation into several islet proteins of apparent M.W. 30-50 kDa. Depletion of islet PKC by prolonged exposure to PMA abolished subsequent secretory and phosphorylating responses to the phorbol ester. However, PKC-depleted islets did not show diminished responses to glucose, suggesting that PKC-mediated phosphorylation of these proteins is not essential for nutrient-induced insulin secretion.
Jones
P M
PM
Biomedical Sciences Division, King's College, London, U.K.
Persaud
S J
SJ
Howell
S L
SL
D000818:Animals; D001345:Autoradiography; D003720:Densitometry / Q000379:methods; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000378:metabolism*; D010539:Permeability; D010766:Phosphorylation; D011493:Protein Kinase C / Q000187:drug effects / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D007328:Insulin; D011506:Proteins; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate