title: Phorbol esters increase adenylate cyclase activity and stability in pituitary membranes.
abstract: In this report, we demonstrate that calcium and phorbol esters enhance cAMP production in GH4C1 cell homogenates. The mechanism for this is a reduction in the rate of decay of adenylate cyclase activity over the course of the assay. Purified protein kinase C can reconstitute calcium- and phorbol ester-dependent adenylate cyclase. Phorbol ester-activated protein kinase C increases both the initial rate of cAMP synthesis and reduces the time-dependent decay of adenylate cyclase activity in membrane preparations. The rate of cAMP production is fit to an equation derived from a model which assumes that adenylate cyclase initially exists in a high activity state which decays exponentially into a low activity state. We suggest that protein kinase C can both prevent the decay of the high activity state and convert the low activity state into the high activity state.
authors.affiliation: Department of Physiology, University of Virginia, Charlottesville 22908.
authors.forename: S T
authors.initials: ST
authors.lastname: Summers
authors.forename: J M
authors.initials: JM
authors.lastname: Walker
authors.forename: J J
authors.initials: JJ
authors.lastname: Sando
authors.forename: M J
authors.initials: MJ
authors.lastname: Cronin
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology; D002462:Cell Membrane / Q000201:enzymology; D000242:Cyclic AMP / Q000096:biosynthesis*; D006801:Humans; D007700:Kinetics; D008954:Models, Biological; D015240:Phorbol 12,13-Dibutyrate; D010703:Phorbol Esters / Q000494:pharmacology*; D010911:Pituitary Neoplasms / Q000201:enzymology*; D011493:Protein Kinase C / Q000378:metabolism* / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D010703:Phorbol Esters; D015240:Phorbol 12,13-Dibutyrate; D000242:Cyclic AMP; D011493:Protein Kinase C; D000262:Adenylyl Cyclases; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium