Author:

Keywords:

SIGNAL TRANSDUCTION, PROTEIN KINASE C, NEOMYCIN, MEDIUM ACIDIFICATION, (SACCHAROMYCES-CEREVISIAE), PROTEIN KINASE-C, ADENYLATE-CYCLASE, SCHIZOSACCHAROMYCES-POMBE, BAKERS-YEAST, PHOSPHORYLATION, STAUROSPORINE, INHIBITOR, MUTANT, ACID, GENE, Science & Technology, Life Sciences & Biomedicine, Biochemistry & Molecular Biology, Cell Biology, Alkaloids, Cell Membrane, Diglycerides, Enzyme Activation, Glucose, Imidazoles, Phosphatidylinositols, Phosphorylation, Proton-Translocating ATPases, Saccharomyces cerevisiae, Signal Transduction, Staurosporine, p-Methoxy-N-methylphenethylamine, 0601 Biochemistry and Cell Biology, 1108 Medical Microbiology, 3101 Biochemistry and cell biology

Abstract:

Addition of glucose to cells of the yeast Saccharomyces cerevisiae causes rapid activation of plasma membrane H+-ATPase and a stimulation of cellular H+ extrusion. We show that addition of diacylglycerol and other activators of protein kinase C to intact cells also activates the H+-ATPase and causes at the same time a stimulation of H+ extrusion from the cells. Both effects are reversed by addition of staurosporine, a protein kinase C inhibitor. Addition of staurosporine or calmidazolium, an inhibitor of Ca2+/calmodulin-dependent protein kinases, separately, causes a partial inhibition of glucose-induced H+-ATPase activation and stimulation of cellular H+ extrusion; together they cause a more potent inhibition. Addition of neomycin, which complexes with phosphatidylinositol 4,5-bisphosphate, or addition of compound 48/80, a phospholipase C inhibitor, also causes near complete inhibition. Diacylglycerol and other protein kinase C activators had no effect on the activity of the K+-uptake system and the activity of trehalase and glucose-induced activation of the K+-uptake system and trehalase was not inhibited by neomycin, supporting the specificity of the effects observed on the H+-ATPase. The results support a model in which glucose-induced activation of H+-ATPase is mediated by a phosphatidylinositol-type signaling pathway triggering phosphorylation of the enzyme both by protein kinase C and one or more Ca2+/calmodulin-dependent protein kinases.