G beta gamma directly binds to the carboxyl terminus of the G protein-gated muscarinic K+ channel, GIRK1

Biochem Biophys Res Commun. 1995 Jul 26;212(3):1022-8. doi: 10.1006/bbrc.1995.2072.


beta gamma Subunits of heterotrimeric GTP-binding proteins (G beta gamma) activate the inwardly rectifying muscarinic K+ channel, GIRK1. The significant role for the carboxyl (C) terminus of GIRK1 in this interaction has been suggested. However, it is still unknown whether G beta gamma directly interacts with GIRK1. To elucidate the molecular basis of G beta gamma-activation of GIRK1, we examined the binding properties of G beta gamma to the C terminus of GIRK1 cloned from mouse brain cDNA library (MB-GIRK1). The C terminus of MB-GIRK1 fused with glutathione S-transferase directly bound to purified G beta gamma. Incubation of the C terminus with Gi pretreated with GTP gamma S, but not with GDP, resulted in the binding of Gi beta gamma to the protein. Purified G alpha-GDP, but not G alpha-GTP gamma S, inhibited the binding of G beta gamma to the fusion protein. These results indicate that G beta gamma dissociated from G alpha may directly bind to the C terminus of GIRK1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Binding Sites / genetics
  • Brain / metabolism
  • Cloning, Molecular
  • DNA, Complementary / genetics
  • G Protein-Coupled Inwardly-Rectifying Potassium Channels
  • GTP-Binding Proteins / chemistry
  • GTP-Binding Proteins / genetics
  • GTP-Binding Proteins / metabolism*
  • In Vitro Techniques
  • Ion Channel Gating
  • Mice
  • Molecular Sequence Data
  • Potassium Channels / chemistry
  • Potassium Channels / genetics
  • Potassium Channels / metabolism*
  • Potassium Channels, Inwardly Rectifying*
  • Protein Conformation
  • Rats
  • Receptors, Muscarinic / chemistry
  • Receptors, Muscarinic / genetics
  • Receptors, Muscarinic / metabolism*
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism


  • DNA, Complementary
  • G Protein-Coupled Inwardly-Rectifying Potassium Channels
  • Potassium Channels
  • Potassium Channels, Inwardly Rectifying
  • Receptors, Muscarinic
  • Recombinant Fusion Proteins
  • GTP-Binding Proteins