Referenced in: none

Automatically associated channels: Kir2.1 , Kir2.4 , Kir3.1 , Kir3.4

Title: Identification of critical residues controlling G protein-gated inwardly rectifying K(+) channel activity through interactions with the beta gamma subunits of G proteins.

Authors: Cheng He, Xixin Yan, Hailin Zhang, Tooraj Mirshahi, Taihao Jin, Aijun Huang, Diomedes E Logothetis

Journal, date & volume: J. Biol. Chem., 2002 Feb 22 , 277, 6088-96

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/11741896

Abstract
G protein-sensitive inwardly rectifying potassium (GIRK) channels are activated through direct interactions of their cytoplasmic N- and C-terminal domains with the beta gamma subunits of G proteins. By using a combination of biochemical and electrophysiological approaches, we identified minimal N- and C-terminal G beta gamma -binding domains responsible for stimulation of GIRK4 channel activity. Within these domains one N-terminal residue, His-64, and one C-terminal residue, Leu-268, proved critical for G beta gamma-mediated GIRK4 activity. Moreover, mutations at these GIRK4 sites reduced significantly binding of the channel domains to G beta gamma . The corresponding residues in GIRK1 also showed a critical involvement in G beta gamma sensitivity. In GIRK4/GIRK1 heteromers the GIRK4 His-64 and Leu-268 residues showed greater contributions to G beta zeta sensitivity than did the corresponding GIRK1 His-57 and Leu-262 residues. These results identify functionally important channel interaction sites with the beta gamma subunits of G proteins, critical for channel activity.