Endocrinology, Vol 125, 2470-2474, Copyright © 1989 by Endocrine Society

ARTICLES

Guanosine triphosphate fulfills a complete and specific nucleotide requirement for luteinizing hormone-induced desensitization of pig ovarian adenylyl cyclase

RC Ekstrom and M Hunzicker-Dunn
Department of Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611.

Homologous desensitization of the ovarian LH-sensitive adenylyl cyclase in cell-free systems is known to be dependent on micromolar concentrations of GTP. In this study, we sought to determine whether the nucleotide requirement of GTP for desensitization is complete and specific. LH-dependent desensitization of the adenylyl cyclase of pig ovarian follicular membranes was examined without adding adenyl-5'-yl imidodiphosphate [AMP-P(NH)P] to prevent the degradation of nucleotide triphosphates. GTP at 0.1 mM or higher [in the absence of AMP-P(NH)P] was able to support the same amount of desensitization (30-35%) that occurs with 1 mM AMP-P(NH)P and micromolar concentrations of GTP. ATP, UTP, and CTP also supported maximal desensitization, but were 5-30 times less potent than GTP. The ED50 value for GTP (14 microM) was about 100 times higher than when the reaction was performed in the presence of 1 mM AMP-P(NH)P; the ED50 values for UTP (70 microM) and CTP and ATP (400 microM) were only 2-5 times higher than when AMP- P(NH)P was included. Incubation of [alpha-32P]GTP with pig follicular membranes demonstrated that 1 mM GTP was stable, whereas 10 microM or less was rapidly degraded unless 1 mM AMP-P(NH)P was included. The specificity of GTP for supporting desensitization was also demonstrated in experiments where guanyl-5'-yl imidodiphosphate, the nonhydrolyzable GTP analog, inhibited LH-induced desensitization which otherwise would have occurred in the presence of ATP, CTP, or UTP. These studies establish the complete and specific requirement of GTP for supporting desensitization of ovarian LH-responsive adenylyl cyclase.

This article has been cited by other articles:

				M. Hunzicker-Dunn, G. Barisas, J. Song, and D. A. Roess Membrane Organization of Luteinizing Hormone Receptors Differs between Actively Signaling and Desensitized Receptors J. Biol. Chem., October 31, 2003; 278(44): 42744 - 42749. [Abstract] [Full Text] [PDF]

				S. Mukherjee, V. V. Gurevich, A. Preninger, H. E. Hamm, M.-F. Bader, A. T. Fazleabas, L. Birnbaumer, and M. Hunzicker-Dunn Aspartic Acid 564 in the Third Cytoplasmic Loop of the Luteinizing Hormone/Choriogonadotropin Receptor Is Crucial for Phosphorylation-independent Interaction with Arrestin2 J. Biol. Chem., May 10, 2002; 277(20): 17916 - 17927. [Abstract] [Full Text] [PDF]

				M. Ascoli, F. Fanelli, and D. L. Segaloff The Lutropin/Choriogonadotropin Receptor, A 2002 Perspective Endocr. Rev., April 1, 2002; 23(2): 141 - 174. [Abstract] [Full Text] [PDF]

				S. Mukherjee, K. Palczewski, V. V. Gurevich, and M. Hunzicker-Dunn beta -Arrestin-dependent Desensitization of Luteinizing Hormone/Choriogonadotropin Receptor Is Prevented by a Synthetic Peptide Corresponding to the Third Intracellular Loop of the Receptor J. Biol. Chem., May 7, 1999; 274(19): 12984 - 12989. [Abstract] [Full Text] [PDF]

				R. M. Rajagopalan-Gupta, S. Mukherjee, X. Zhu, Y.-K. Ho, H. Hamm, M. Birnbaumer, L. Birnbaumer, and M. Hunzicker-Dunn Roles of Gi and Gq/11 in Mediating Desensitization of the Luteinizing Hormone/Choriogonadotropin Receptor in Porcine Ovarian Follicular Membranes Endocrinology, April 1, 1999; 140(4): 1612 - 1621. [Abstract] [Full Text]

				S. Mukherjee, K. Palczewski, V. Gurevich, J. L. Benovic, J. P. Banga, and M. Hunzicker-Dunn A direct role for arrestins in desensitization of the luteinizing hormone/choriogonadotropin receptor in porcine ovarian follicular membranes PNAS, January 19, 1999; 96(2): 493 - 498. [Abstract] [Full Text] [PDF]

				M. L. G. Lamm, R. M. Rajagopalan-Gupta, and M. Hunzicker-Dunn Epidermal Growth Factor-Induced Heterologous Desensitization of the Luteinizing Hormone/Choriogonadotopin Receptor in a Cell-Free Membrane Preparation Is Associated with the Tyrosine Phosphorylation of the Epidermal Growth Factor Receptor Endocrinology, January 1, 1999; 140(1): 29 - 36. [Abstract] [Full Text]

				Z. Wang, X. Liu, and M. Ascoli Phosphorylation of the Lutropin/Choriogonadotropin Receptor Facilitates Uncoupling of the Receptor from Adenylyl Cyclase and Endocytosis of the Bound Hormone Mol. Endocrinol., February 1, 1997; 11(2): 183 - 192. [Abstract] [Full Text]

				S. Mukherjee, J. E. Casanova, and M. Hunzicker-Dunn Desensitization of the Luteinizing Hormone/Choriogonadotropin Receptor in Ovarian Follicular Membranes Is Inhibited by Catalytically Inactive ARNO+ J. Biol. Chem., February 23, 2001; 276(9): 6524 - 6528. [Abstract] [Full Text] [PDF]

				S. Mukherjee, V. V. Gurevich, J. C. R. Jones, J. E. Casanova, S. R. Frank, E. T. Maizels, M.-F. Bader, R. A. Kahn, K. Palczewski, K. Aktories, et al. The ADP ribosylation factor nucleotide exchange factor ARNO promotes beta -arrestin release necessary for luteinizing hormone/choriogonadotropin receptor desensitization PNAS, May 23, 2000; 97(11): 5901 - 5906. [Abstract] [Full Text] [PDF]