Agonist-induced formation of unproductive receptor-G12 complexes

Najeah Okashah, Shane C. Wright, Kouki Kawakami, Signe Mathiasen, Joris Zhou, Sumin Lu, Jonathan A. Javitch, Asuka Inoue, Michel Bouvier, Nevin A. Lambert

Research output: Contribution to journalArticle

Abstract

G proteins are activated when they associate with G protein-coupled receptors (GPCRs), often in response to agonist-mediated receptor activation. It is generally thought that agonist-induced receptor-G protein association necessarily promotes G protein activation and, conversely, that activated GPCRs do not interact with G proteins that they do not activate. Here we show that GPCRs can form agonist-dependent complexes with G proteins that they do not activate. Using cell-based bioluminescence resonance energy transfer (BRET) and luminescence assays we find that vasopressin V2 receptors (V2R) associate with both Gs and G12 heterotrimers when stimulated with the agonist arginine vasopressin (AVP). However, unlike V2R-Gs complexes, V2R-G12 complexes are not destabilized by guanine nucleotides and do not promote G12 activation. Activating V2R does not lead to signaling responses downstream of G12 activation, but instead inhibits basal G12-mediated signaling, presumably by sequestering G12 heterotrimers. Overexpressing G12 inhibits G protein receptor kinase (GRK) and arrestin recruitment to V2R and receptor internalization. Formyl peptide (FPR1 and FPR2) and Smoothened (Smo) receptors also form complexes with G12 that are insensitive to nucleotides, suggesting that unproductive GPCR-G12 complexes are not unique to V2R. These results indicate that agonist-dependent receptor-G protein association does not always lead to G protein activation and may in fact inhibit G protein activation.

Original languageEnglish (US)
Pages (from-to)21723-21730
Number of pages8
JournalProceedings of the National Academy of Sciences of the United States of America
Volume117
Issue number35
DOIs
StatePublished - Sep 1 2020

Keywords

  • Arrestin
  • G protein-coupled receptor
  • GPCR
  • Ternary complex

ASJC Scopus subject areas

  • General

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