A discrete alcohol pocket involved in GIRK channel activation.
Ethanol modifies neural activity in the brain by modulating ion channels. Ethanol activates G protein-gated inwardly rectifying K(+) channels, but the molecular mechanism is not well understood. Here, we used a crystal structure of a mouse inward rectifier containing a bound alcohol and structure-based mutagenesis to probe a putative alcohol-binding pocket located in the cytoplasmic domains of GIRK channels. Substitutions with bulkier side-chains in the alcohol-binding pocket reduced or eliminated activation by alcohols. By contrast, alcohols inhibited constitutively open channels, such as IRK1 or GIRK2 engineered to strongly bind PIP(2). Mutations in the hydrophobic alcohol-binding pocket of these channels had no effect on alcohol-dependent inhibition, suggesting an alternate site is involved in inhibition. Comparison of high-resolution structures of inwardly rectifying K(+) channels suggests a model for activation of GIRK channels using this hydrophobic alcohol-binding pocket. These results provide a tool for developing therapeutic compounds that could mitigate the effects of alcohol.
Aryal
Prafulla
P
Peptide Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California, USA.
Dvir
Hay
H
Choe
Senyon
S
Slesinger
Paul A
PA
D000818:Animals; D001665:Binding Sites / Q000502:physiology; D002417:Cattle; D002460:Cell Line; D002492:Central Nervous System Depressants / Q000494:pharmacology*; D018360:Crystallography, X-Ray; D000431:Ethanol / Q000494:pharmacology*; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D051379:Mice; D008958:Models, Molecular; D016296:Mutagenesis; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism; D024661:Potassium Channels, Inwardly Rectifying / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D051381:Rats
D002492:Central Nervous System Depressants; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels; D019269:Phosphatidylinositol 4,5-Diphosphate; D024661:Potassium Channels, Inwardly Rectifying; D000431:Ethanol