Alcohol (ethanol) consumption alters neural activity in the brain by modulating different types of ion channels. An emerging concept in the field is that some of the physiological effects of ethanol are mediated by direct modulation of ion channels in the brain. One of the targets in the brain for ethanol is the G protein-gated inwardly rectifying potassium (GIRK) channel, which is activated by ethanol. Mice lacking GIRK2 channels exhibit diminished ethanol-induced tolerance to pain and self-administer more ethanol than wild-type mice. Moreover, a quantitative trait loci with a large effect on predisposition to sedative withdrawal, such as from ethanol, was narrowed to a region on chromosome 1 in mice that contains Girk3 gene. GIRK3 knockout mice exhibit less severe sedative-hypnotic withdrawal. Though GIRK2 and GIRK2/3 channels are implicated in ethanol-related behaviors, the molecular mechanism underlying this response is not well understood. Recently, we showed with high-resolution structural studies that alcohols bind directly to hydrophobic pockets of inwardly rectifying potassium channels. Mutations in the alcohol-binding pocket of GIRK2 channels significantly alter ethanol activation. We hypothesize that ethanol binds to hydrophobic pockets in GIRK2/3 channels and facilitate a conformational change that is relayed to the channel's gate and opens the channel. In this research proposal, we plan to use an innovative approach of high-resolution crystallographic studies, structure-based mutagenesis and advanced electrophysiological recordings to investigate this hypothesis. Specifically, we will conduct a structure-function analysis of the ethanol-binding pocket in GIRK2/3 channels (1), solve high-resolution structures of GIRK channels complexed with ethanol to reveal conformational changes in the channel protein that occur with ethanol-dependent gating (2), and elaborate mechanistic models for ethanol-dependent activation of GIRK channels, utilizing single-channel recordings and chemical modification of cysteine-substituted channels (3). Completion of these proposed experiments will reveal the structural basis of ethanol modulation of GIRK channels, which will provide insights into the mechanism of ethanol-modulation of other types of ion channels. Understanding the molecular mechanism underlying ethanol modulation of ion channels could lead to development of novel pharmaceutical agents for treating alcohol-dependence, directly benefiting human health.

Public Health Relevance

Ethanol, a major drug of addiction and abuse in the U.S., directly modulates brain ion channels, which control the excitability of brain neurons. The goal of this grant is to investigate the molecular and structural mechanisms underlying ethanol-dependent activation of neuronal potassium channels. Results from these studies could lead to the development of novel pharmaceutical agents that specifically modulate potassium channels or antagonize actions of ethanol.

National Institute of Health (NIH)
National Institute on Alcohol Abuse and Alcoholism (NIAAA)
Research Project (R01)
Project #
Application #
Study Section
Neurotoxicology and Alcohol Study Section (NAL)
Program Officer
Liu, Qi-Ying
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Icahn School of Medicine at Mount Sinai
Schools of Medicine
New York
United States
Zip Code
Munoz, Michaelanne B; Padgett, Claire L; Rifkin, Robert et al. (2016) A Role for the GIRK3 Subunit in Methamphetamine-Induced Attenuation of GABAB Receptor-Activated GIRK Currents in VTA Dopamine Neurons. J Neurosci 36:3106-14
Herman, Melissa A; Sidhu, Harpreet; Stouffer, David G et al. (2015) GIRK3 gates activation of the mesolimbic dopaminergic pathway by ethanol. Proc Natl Acad Sci U S A 112:7091-6
Glaaser, Ian W; Slesinger, Paul A (2015) Structural Insights into GIRK Channel Function. Int Rev Neurobiol 123:117-60
Munoz, Michaelanne B; Slesinger, Paul A (2014) Sorting nexin 27 regulation of G protein-gated inwardly rectifying K⁺ channels attenuates in vivo cocaine response. Neuron 82:659-69
Bodhinathan, Karthik; Slesinger, Paul A (2014) Alcohol modulation of G-protein-gated inwardly rectifying potassium channels: from binding to therapeutics. Front Physiol 5:76
Balana, Bartosz; Bahima, Laia; Bodhinathan, Karthik et al. (2013) Ras-association domain of sorting Nexin 27 is critical for regulating expression of GIRK potassium channels. PLoS One 8:e59800
Bodhinathan, Karthik; Slesinger, Paul A (2013) Molecular mechanism underlying ethanol activation of G-protein-gated inwardly rectifying potassium channels. Proc Natl Acad Sci U S A 110:18309-14
Klammt, Christian; Maslennikov, Innokentiy; Bayrhuber, Monika et al. (2012) Facile backbone structure determination of human membrane proteins by NMR spectroscopy. Nat Methods 9:834-9
Howard, Rebecca J; Slesinger, Paul A; Davies, Daryl L et al. (2011) Alcohol-binding sites in distinct brain proteins: the quest for atomic level resolution. Alcohol Clin Exp Res 35:1561-73
Balana, Bartosz; Taylor, Natalie; Slesinger, Paul A (2010) Mutagenesis and functional analysis of ion channels heterologously expressed in mammalian cells. J Vis Exp :