Cell-free lutropin-dependent desensitization of the lutropin-sensitive adenylate cyclase of pig ovarian follicles is dependent on ATP
| Autor: | M Hunzicker-Dunn, S C Kuemmerle |
|---|---|
| Rok vydání: | 1984 |
| Předmět: |
GTP'
Swine medicine.medical_treatment Adenylyl Imidodiphosphate Adenylate kinase Biology In Vitro Techniques Biochemistry Cyclase Adenosine Triphosphate Ovarian Follicle Follicular phase medicine Animals Nucleotide heterocyclic compounds Molecular Biology Desensitization (medicine) chemistry.chemical_classification Guanylyl Imidodiphosphate Cell-Free System Cell Biology Luteinizing Hormone Adenosine Enzyme Activation Membrane chemistry Female Guanosine Triphosphate medicine.drug Adenylyl Cyclases Research Article |
| Zdroj: | The Biochemical journal. 223(3) |
| ISSN: | 0264-6021 |
| Popis: | Experiments were conducted to clarify the nucleotide requirements for lutropin (LH)-dependent adenylate cyclase desensitization in a cell-free membrane preparation derived from a thecal-cell-enriched component of preovulatory pig ovarian follicles. The follicular membranes were extensively washed in 2M-urea to remove endogenously bound GTP, and ATP devoid of GTP was utilized. Results conducted in the presence of 60 microM-GTP and various concentrations of ATP confirm the dependence of LH-stimulated adenylate cyclase activation and desensitization on millimolar concentrations of ATP. In experiments in which adenylate cyclase activation was supported by Mg2+, LH and adenosine 5′-[beta, gamma-imido]triphosphate, GTP did not support the desensitization response. Moreover, although GTP increased both basal and LH-stimulable adenylate cyclase activities in a concentration-dependent manner, the percentage desensitization was not significantly modified by the presence of 10nM-10mM-GTP. These results demonstrate that, even in the presence of exogenous GTP and Mg2+, activation of adenylate cyclase by saturating concentrations of LH in the presence of adenosine 5′-[beta, gamma-imido]triphosphate is not sufficient to initiate desensitization; millimolar concentrations of ATP are also required for the adenylate cyclase desensitization response. |
| Databáze: | OpenAIRE |
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