A regulator of G protein signalling (RGS) protein confers agonist-dependent relaxation gating to a G protein-gated K+ channel

J Physiol. 2000 Jul 15;526 Pt 2(Pt 2):341-7. doi: 10.1111/j.1469-7793.2000.00341.x.

Abstract

1. The effects of RGS4 on the voltage-dependent relaxation of G protein-gated K+ (KG) channels were examined by heterologous expression in Xenopus oocytes. 2. While the relaxation kinetics was unaffected by the acetylcholine concentration ([ACh]) in the absence of RGS4, it became dependent on [ACh] when RGS4 was co-expressed. 3. Kinetic analyses indicated that RGS4 confers to the KG channel a voltage-independent inhibitory gating mechanism, which was attenuated by ACh in a concentration-dependent fashion. 4. In vitro biochemical studies showed that RGS4 could bind to the protein complex containing KG channel subunits. 5. Since the native cardiac KG channel exhibited similar agonist-dependent relaxation kinetics to that mediated by RGS4, it is suggested that KG channel gating is a novel physiological target of RGS protein-mediated regulation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylcholine / pharmacology*
  • Animals
  • Calcium-Calmodulin-Dependent Protein Kinases / antagonists & inhibitors
  • Female
  • GTP-Binding Proteins / physiology*
  • Ion Channel Gating / physiology
  • Membrane Potentials / drug effects
  • Membrane Potentials / physiology
  • Oocytes / physiology
  • Potassium Channels / genetics
  • Potassium Channels / physiology*
  • Potassium Channels, Inwardly Rectifying*
  • RGS Proteins / physiology*
  • Rats
  • Recombinant Proteins / metabolism
  • Xenopus laevis

Substances

  • Potassium Channels
  • Potassium Channels, Inwardly Rectifying
  • RGS Proteins
  • Recombinant Proteins
  • RGS4 protein
  • Calcium-Calmodulin-Dependent Protein Kinases
  • GTP-Binding Proteins
  • Acetylcholine