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The ADP ribosylation factor nucleotide exchange factor ARNO promotes beta-arrestin release necessary for luteinizing hormone/choriogonadotropin receptor desensitization.

Mukherjee S, Gurevich VV, Jones JC, Casanova JE, Frank SR, Maizels ET, Bader MF, Kahn RA, Palczewski K, Aktories K, Hunzicker-Dunn M
Proc Natl Acad Sci U S A. 2000 97 (11): 5901-6

PMID: 10811902 · PMCID: PMC18531 · DOI:10.1073/pnas.100127097

Desensitization of guanine nucleotide binding protein-coupled receptors is a ubiquitous phenomenon characterized by declining effector activity upon persistent agonist stimulation. The luteinizing hormone/choriogonadotropin receptor (LH/CGR) in ovarian follicles exhibits desensitization of effector adenylyl cyclase activity in response to the mid-cycle surge of LH. We have previously shown that uncoupling of the agonist-activated LH/CGR from the stimulatory G protein (G(s)) is dependent on GTP and attributable to binding of beta-arrestin present in adenylyl cyclase-rich follicular membrane fraction to the third intracellular (3i) loop of the receptor. Here, we report that LH/CGR-dependent desensitization is mimicked by ADP ribosylation factor nucleotide-binding site opener, a guanine nucleotide exchange factor of the small G proteins ADP ribosylation factors (Arfs) 1 and 6, and blocked by synthetic N-terminal Arf6 peptide, suggesting that the GTP-dependent step of LH/CGR desensitization is receptor-dependent Arf6 activation. Arf activation by GTP and ADP ribosylation factor nucelotide-binding site opener promotes the release of docked beta-arrestin from the membrane, making beta-arrestin available for LH/CGR; Arf6 but not Arf1 peptides block beta-arrestin release from the membrane. Thus, LH/CGR appears to activate two membrane delimited signaling cascades via two types of G proteins: heterotrimeric G(s) and small G protein Arf6. Arf6 activation releases docked beta-arrestin necessary for receptor desensitization, providing a feedback mechanism for receptor self-regulation.

MeSH Terms (24)

Adenylyl Cyclases ADP-Ribosylation Factors Animals Arrestins beta-Arrestins Cell-Free System Chorionic Gonadotropin Feedback Female Gonadotropins, Equine Granulosa Cells GTP-Binding Protein alpha Subunits, Gs GTPase-Activating Proteins Guanosine Triphosphate Luteinizing Hormone Ovarian Follicle Ovulation Induction Peptide Fragments Protein Binding Rats Receptors, LH Recombinant Fusion Proteins Signal Transduction Swine

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