title: Regulation of phosphoinositide breakdown by guanine nucleotides.
abstract: Phosphoinositide hydrolysis is coupled to receptor systems involved in the elevation of cytosolic Ca2+ and activation of protein kinase C. In cell-free systems, guanine nucleotides are required to transduce the effects of receptor activation to phosphoinositide breakdown. Non-hydrolyzable guanine nucleotides stimulate phosphoinositide breakdown in permeabilized cells as well as membranes prepared from salivary glands, GH3 cells, neutrophils, hepatocytes and cerebral cortical tissue. In blowfly salivary gland membranes, 5-hydroxytryptamine stimulates a guanine-nucleotide dependent breakdown of both endogenous and exogenous phosphoinositide substrate through activation of phospholipase C. These data suggest that a GTP-binding protein modulates phospholipase C activity. The identity of this GTP-binding protein has not been established but may resemble other regulatory GTP-binding proteins which have been identified as transducing proteins in a variety of receptor systems.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000502:physiology; D002772:Cholera Toxin / Q000494:pharmacology; D000242:Cyclic AMP / Q000502:physiology; D004789:Enzyme Activation; D019204:GTP-Binding Proteins / Q000502:physiology*; D006150:Guanine Nucleotides / Q000502:physiology*; D006160:Guanosine Triphosphate / Q000502:physiology; D006801:Humans; D008565:Membrane Proteins / Q000502:physiology; D010716:Phosphatidylinositols / Q000378:metabolism*; D015293:Transducin; D010738:Type C Phospholipases / Q000378:metabolism; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
chemical_list: D006150:Guanine Nucleotides; D008565:Membrane Proteins; D010716:Phosphatidylinositols; D010566:Virulence Factors, Bordetella; D006160:Guanosine Triphosphate; D002772:Cholera Toxin; D000242:Cyclic AMP; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins; D015293:Transducin; D000262:Adenylyl Cyclases; D002118:Calcium