title: Adenylate cyclase in Xenopus laevis oocytes: characterization of the progesterone-sensitive, membrane-bound form.
abstract: Progesterone-induced reinitiation of meiosis in Xenopus laevis oocytes involves a decrease in cAMP level. In these cells, adenylate cyclase is compartmentalized, with 25-30% in the plasma membrane fraction P-10000 (sedimenting at 10000 X g) and greater than 50% in the cytosol. Soluble adenylate cyclase appears not to be regulated via a GTP-binding regulatory protein (G/F) and is insensitive to progesterone. In contrast, membrane-bound adenylate cyclase seems to be linked to G/F, since it is stimulated by sodium fluoride, guanyl-5'-imidodiphosphate (Gpp(NH)p) and by cholera toxin; it is also inhibited by progesterone. The steroid inhibition is displayed towards basal and stimulated activities. The extent of progesterone inhibition of basal activity is dependent on Mg2+ and Mn2+ concentrations. The hormonal effect is independent of GTP concentration and is observed even in the presence of the non-hydrolysable analogue of GTP, Gpp(NH)p. The progesterone effect is not mediated by adenosine. Exposure of the P-10000 fraction to 5'-deoxy-5'-S-isobutylthioadenosine (a methyltransferase inhibitor) increases adenylate cyclase activity.
mesh_terms: D015720:5'-Nucleotidase; D000067956:Adenylyl Cyclase Inhibitors; D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D001798:Blood Proteins / Q000502:physiology; D002462:Cell Membrane / Q000201:enzymology; D004789:Enzyme Activation; D005260:Female; D019204:GTP-Binding Proteins; D009708:Nucleotidases / Q000378:metabolism; D009865:Oocytes / Q000201:enzymology*; D010063:Ovum / Q000201:enzymology*; D043264:Phosphodiesterase I; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D011374:Progesterone / Q000494:pharmacology*; D011506:Proteins / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000502:physiology; D013347:Subcellular Fractions / Q000201:enzymology; D014982:Xenopus laevis
chemical_list: D000067956:Adenylyl Cyclase Inhibitors; D001798:Blood Proteins; D011506:Proteins; D011956:Receptors, Cell Surface; D011374:Progesterone; D009708:Nucleotidases; D015720:5'-Nucleotidase; D010727:Phosphoric Diester Hydrolases; D043264:Phosphodiesterase I; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases