title: Reversal of the desensitized state of pig ovarian follicular human choriogonadotropin-sensitive adenylylcyclase by guanosine 5'-O-(2-thiodiphosphate).
abstract: We investigated the stability of the desensitized state of the human choriogonadotropin (hCG)-sensitive adenylylcyclase of the pig ovarian follicle. A 20,000 x g membrane preparation of pig follicular membranes was incubated under conditions which resulted in the hormone-induced desensitization of the hCG-responsive adenylylcyclase. The desensitized state was maintained upon subsequent incubation of the membranes with GTP, GDP, GMP, ATP, ADP, AMP, CTP, UTP, adenyl-5'-yl imidodiphosphate (AMP-P(NH)P), and adenyl (beta, gamma-methylene)-diphosphonate (AMP-P(CH2)P); however, the desensitized state was reverted to a fully active state upon incubation with guanosine 5'-O-(2-thiodiphosphate) (GDP beta S) and guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S). The reversal effect of GDP beta S on hCG-responsive adenylylcyclase activity was time- and temperature-dependent, and showed a selectivity for GDP beta S over adenosine 5'-O-(2-thiodiphosphate) (ADP beta S) (half-maximal effective dose of 12 microM versus 260 microM, respectively). GDP beta S had no effect on the binding affinity or apparent number of luteinizing hormone (LH)/CG receptors or on the dissociation rate of 125I-hCG from the receptor. GDP beta S promoted an hCG- and time-dependent release of guanine nucleotides from the membranes. A model is proposed which accounts for the unique characteristics of LH/CG-sensitive adenylylcyclase desensitization and subsequent reactivation by GDP beta S.
authors.affiliation: Department of Cell, Molecular, and Structural Biology, Northwestern University Medical School, Chicago, Illinois 60611.
authors.forename: R C
authors.initials: RC
authors.lastname: Ekstrom
authors.forename: E M
authors.initials: EM
authors.lastname: Carney
authors.forename: M L
authors.initials: ML
authors.lastname: Lamm
authors.forename: M
authors.initials: M
authors.lastname: Hunzicker-Dunn
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D006063:Chorionic Gonadotropin / Q000494:pharmacology*; D005260:Female; D019204:GTP-Binding Proteins / Q000502:physiology; D006150:Guanine Nucleotides / Q000378:metabolism; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000494:pharmacology; D009711:Nucleotides / Q000494:pharmacology; D006080:Ovarian Follicle / Q000201:enzymology*; D011974:Receptors, LH / Q000502:physiology; D013552:Swine; D013696:Temperature; D013873:Thionucleotides / Q000494:pharmacology*
chemical_list: D006063:Chorionic Gonadotropin; D006150:Guanine Nucleotides; D009711:Nucleotides; D011974:Receptors, LH; D013873:Thionucleotides; D006153:Guanosine Diphosphate; C023427:guanosine 5'-O-(2-thiodiphosphate); D006160:Guanosine Triphosphate; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases