Selective regulation of Gα(q/11) by an RGS domain in the G protein- coupled receptor kinase, GRK2

Christopher V. Carman, Jean Luc Parent, Peter W. Day, Alexey N. Pronin, Pamela M. Sternweis, Philip B. Wedegaertner, Alfred G. Gilman, Jeffrey L. Benovic, Tohru Kozasa

Research output: Contribution to journalArticlepeer-review

267 Scopus citations

Abstract

G protein-coupled receptor kinases (GRKs) are well characterized regulators of G protein-coupled receptors, whereas regulators of G protein signaling (RGS) proteins directly control the activity of G protein α subunits. Interestingly, a recent report (Siderovski, D. P., Hessel, A., Chung, S., Mak, T. W., and Tyers, M. (1996) Curr. Biol. 6, 211-212) identified a region within the N terminus of GRKs that contained homology to RGS domains. Given that RGS domains demonstrate AlF4/--dependent binding to G protein α subunits, we tested the ability of G proteins from a crude bovine brain extract to bind to GRK affinity columns in the absence or presence of AlF4/-. This revealed the specific ability of bovine brain Gα(q/11) to bind to both GRK2 and GRK3 in an AlF4/--dependent manner. In contrast, Gα(s), Gα(i), and Gα(12/13) did not bind to GRK2 or GRK3 despite their presence in the extract. Additional studies revealed that bovine brain G2a(q11) could also bind to an N-terminal construct of GRK2, while no binding of Gα(q/11), Gα(s), Gα(i), or Gα(12/13) to comparable constructs of GRK5 or GRK6 was observed. Experiments using purified Gα(q) revealed significant binding of both Gα(q) GDP/AlF4/- and Gα(q)(GTPγS), but not Gα(q)(GDP), to GRK2. Activation-dependent binding was also observed in both COS-1 and HEK293 cells as GRK2 significantly co-immunoprecipitated constitutively active Gα(q)(R183C) but not wild type Gα(q). In vitro analysis revealed that GRK2 possesses weak GAP activity toward Gα(q) that is dependent on the presence of a G protein-coupled receptor. However, GRK2 effectively inhibited Gα(q)-mediated activation of phospholipase C-β both in vitro and in cells, possibly through sequestration of activated Gα(q). These data suggest that a subfamily of the GRKs may be bifunctional regulators of G protein-coupled receptor signaling operating directly on both receptors and G proteins.

Original languageEnglish (US)
Pages (from-to)34483-34492
Number of pages10
JournalJournal of Biological Chemistry
Volume274
Issue number48
DOIs
StatePublished - Nov 26 1999

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Fingerprint Dive into the research topics of 'Selective regulation of Gα(q/11) by an RGS domain in the G protein- coupled receptor kinase, GRK2'. Together they form a unique fingerprint.

Cite this