Recruitment of RGS2 and RGS4 to the plasma membrane by G proteins and receptors reflects functional interactions

Mol Pharmacol. 2003 Sep;64(3):587-93. doi: 10.1124/mol.64.3.587.

Abstract

N-terminally green fluorescent protein (GFP)-tagged regulator of G protein signaling (RGS) 2 and RGS4 fusion proteins expressed in human embryonic kidney 293 cells localized to the nucleus and cytosol, respectively. They were selectively recruited to the plasma membrane by G proteins and correspondingly by receptors that activate those G proteins: GFP-RGS2 when coexpressed with Galphas, beta2-adrenergic receptor, Galphaq, or AT1A angiotensin II receptor, and GFP-RGS4 when coexpressed with Galphai2 or M2 muscarinic receptor. G protein mutants with reduced RGS affinity did not produce this effect, implying that the recruitment involves direct binding to G proteins and is independent of downstream signaling events. Neither agonists nor inverse agonists altered receptor-promoted RGS association with the plasma membrane, and expressing either constitutively activated or poorly activated G protein mutants produced effects similar to those of their wild-type counterparts. Thus, intracellular interactions between these proteins seem to be relatively stable and insensitive to the activation state of the G protein, in contrast to the transient increases in RGS-G protein association known to be caused by G protein activation in solution-based assays. G protein effects on RGS localization were mirrored by RGS effects on G protein function. RGS4 was more potent than RGS2 in promoting steady-state Gi GTPase activity, whereas RGS2 inhibited Gs-dependent increases in intracellular cAMP, suggesting that G protein signaling in cells is regulated by the selective recruitment of RGS proteins to the plasma membrane.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • COS Cells
  • Cell Line
  • Cell Membrane / metabolism
  • Cell Membrane / physiology
  • Chlorocebus aethiops
  • Dose-Response Relationship, Drug
  • GTP-Binding Proteins / metabolism*
  • GTP-Binding Proteins / physiology
  • Humans
  • Intracellular Fluid / metabolism
  • Intracellular Fluid / physiology
  • Protein Transport
  • RGS Proteins / metabolism*
  • RGS Proteins / physiology
  • Receptors, Cell Surface / agonists
  • Receptors, Cell Surface / metabolism*
  • Receptors, Cell Surface / physiology

Substances

  • RGS Proteins
  • RGS2 protein, human
  • Receptors, Cell Surface
  • RGS4 protein
  • GTP-Binding Proteins