Phosphorylation-independent desensitization of the luteinizing hormone/chorionic gonadotropin receptor in porcine follicular membranes

Marilyn L G Lamm, Mary Hunzicker-Dunn*

*Corresponding author for this work

Research output: Contribution to journalArticle

33 Scopus citations

Abstract

Phosphorylation of several G protein-coupled receptors mediates desensitization. This study determined whether LH/CG receptor was phosphorylated under conditions that promoted human CG (hCG)-induced desensitization. Cell-free desensitization of LH/CG receptor-mediated adenylylcyclase activity in porcine follicular membranes occurred in the presence of GTP and was time- and hCG dose-dependent, reaching 36-52% upon preincubation at 30 C for 40 min with 1.0 μg/ml hCG. However, under conditions that promoted GTP-dependent desensitization, there was no apparent phosphorylation of LH/CG receptor (obtained via immunoprecipitation) by endogenous membrane-associated protein kinases using [γ-32P]GTP or [γ-32P]ATP as phosphate donor. On the other hand, LH/CG receptor (88-90 kilodaltons) from both control and hCG-incubated membranes was phosphorylated in vitro by the catalytic subunit of cAMP-dependent protein kinase (protein kinase A). However, protein kinase A (in the absence of exogenous GTP) did not promote LH/CG receptor desensitization. These data demonstrate that, unlike with other G protein-linked receptors, LH/CG receptor phosphorylation by endogenous follicular membrane-associated protein kinase(s) does not mediate desensitization.

Original languageEnglish (US)
Pages (from-to)1537-1546
Number of pages10
JournalMolecular Endocrinology
Volume8
Issue number11
DOIs
StatePublished - Jan 1 1994

ASJC Scopus subject areas

  • Molecular Biology
  • Endocrinology

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