Human fat cell adenylate cyclase. Modulation of parathyroid hormone action by guanine nucleotides.
The effects of guanine nucleotides on basal and parathyroid hormone-stimulated adenylate cyclase of human fat cell ghosts were studied. GTP (10(-7)-10(-3) M) caused a dose-dependent inhibition of basal enzyme activity, but it had no significant effect on PTH-stimulated rates of cAMP-formation. The guanine nucleotide analogue 5'-guanylyl-imidodiphosphate GMP (PNP) when applied in the same concentration range, stimulated basal as well as PTH-activated adenylate cyclase activity up to 300%. GMP (PNP) activation was non-linear with time. PTH-activated the human fat cell adenylate cyclase via an individual receptor distinct from beta-adrenergic receptor sites.
D000262:Adenylyl Cyclases / Q000378:metabolism*; D000273:Adipose Tissue / Q000201:enzymology*; D000242:Cyclic AMP / Q000378:metabolism; D004837:Epinephrine / Q000494:pharmacology; D006150:Guanine Nucleotides / Q000494:pharmacology*; D006157:Guanosine Monophosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D010281:Parathyroid Hormone / Q000494:pharmacology*; D010761:Phosphorus Radioisotopes
D006150:Guanine Nucleotides; D010281:Parathyroid Hormone; D010761:Phosphorus Radioisotopes; D006157:Guanosine Monophosphate; D006160:Guanosine Triphosphate; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; D004837:Epinephrine