title: Islet-activating protein prevents nicotinic acid-induced GTPase stimulation and GTP but not GTP gamma S-induced adenylate cyclase inhibition in rat adipocytes.
abstract: The influence of islet-activating protein (IAP), a Bordetella pertussis toxin, was studied on adenylate cyclase and GTPase activities in rat adipocyte membranes. Pretreatment of rats or intact rat adipocytes with IAP did not affect adenylate cyclase inhibition by the stable GTP analog, GTP gamma S, whereas inhibition by GTP was abolished. Concomitantly, activation of the adipocyte enzyme by sodium and its inhibition by nicotinic acid were prevented. Furthermore, IAP treatment of adipocyte membranes prevented nicotinic acid-induced stimulation of a high affinity GTPase. The data suggest that a GTP-hydrolyzing system involved in the inhibitory regulation of adenylate cyclase is the target of IAP's action.
mesh_terms: D037361:Adenylate Cyclase Toxin; D000067956:Adenylyl Cyclase Inhibitors; D000273:Adipose Tissue / Q000201:enzymology*; D000818:Animals; D001426:Bacterial Proteins / Q000494:pharmacology*; D002462:Cell Membrane / Q000201:enzymology; D005576:Colforsin; D004224:Diterpenes / Q000494:pharmacology; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D009539:Nicotinic Acids / Q000494:pharmacology; D037342:Pertussis Toxin; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D051381:Rats; D012965:Sodium Chloride / Q000494:pharmacology; D013873:Thionucleotides / Q000494:pharmacology; D010566:Virulence Factors, Bordetella
chemical_list: D037361:Adenylate Cyclase Toxin; D000067956:Adenylyl Cyclase Inhibitors; D001426:Bacterial Proteins; D004224:Diterpenes; D009539:Nicotinic Acids; D013873:Thionucleotides; D010566:Virulence Factors, Bordetella; D005576:Colforsin; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D012965:Sodium Chloride; D006160:Guanosine Triphosphate; D037342:Pertussis Toxin; D010744:Phosphoric Monoester Hydrolases; D020558:GTP Phosphohydrolases