Referenced in: none

Automatically associated channels: Kir2.2 , Kir3.2

Title: Pertussis-toxin-sensitive Galpha subunits selectively bind to C-terminal domain of neuronal GIRK channels: evidence for a heterotrimeric G-protein-channel complex.

Authors: Sinead M Clancy, Catherine E Fowler, Melissa Finley, Ka Fai Suen, Christine Arrabit, Frédérique Berton, Tohru Kosaza, Patrick J Casey, Paul A Slesinger

Journal, date & volume: Mol. Cell. Neurosci., 2005 Feb , 28, 375-89

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/15691717

Abstract
Neuronal G-protein-gated inwardly rectifying potassium (Kir3; GIRK) channels are activated by G-protein-coupled receptors that selectively interact with PTX-sensitive (Galphai/o) G proteins. Although the Gbetagamma dimer is known to activate GIRK channels, the role of the Galphai/o subunit remains unclear. Here, we established that Galphao subunits co-immunoprecipitate with neuronal GIRK channels. In vitro binding studies led to the identification of six amino acids in the GIRK2 C-terminal domain essential for Galphao binding. Further studies suggested that the Galphai/obetagamma heterotrimer binds to the GIRK2 C-terminal domain via Galpha and not Gbetagamma. Galphai/o binding-impaired GIRK2 channels exhibited reduced receptor-activated currents, but retained normal ethanol- and Gbetagamma-activated currents. Finally, PTX-insensitive Galphaq or Galphas subunits did not bind to the GIRK2 C-terminus. Together, these results suggest that the interaction of PTX-sensitive Galphai/o subunit with the GIRK2 C-terminal domain regulates G-protein receptor coupling, and may be important for establishing specific Galphai/o signaling pathways.