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Updated: Feb 12, 2026

High-throughput Screening for Small-molecule Modulators of Inward Rectifier Potassium Channels
Published on: January 27, 2013
Structural basis for the ethanol action on G-protein-activated inwardly rectifying potassium channel 1 revealed by
Yuki Toyama1,2, Hanaho Kano1, Yoko Mase1
1Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, 113-0033 Tokyo, Japan.
Abstract:
Ethanol consumption leads to a wide range of pharmacological effects by acting on the signaling proteins in the human nervous system, such as ion channels. Despite its familiarity and biological importance, very little is known about the molecular mechanisms underlying the ethanol action, due to extremely weak binding affinity and the dynamic nature of the ethanol interaction. In this research, we focused on the primary in vivo target of ethanol, G-protein-activated inwardly rectifying potassium channel (GIRK), which is responsible for the ethanol-induced analgesia. By utilizing solution NMR spectroscopy, we characterized the changes in the structure and dynamics of GIRK induced by ethanol binding. We demonstrated here that ethanol binds to GIRK with an apparent dissociation constant of 1.0 M and that the actual physiological binding site of ethanol is located on the cavity formed between the neighboring cytoplasmic regions of the GIRK tetramer. From the methyl-based NMR relaxation analyses, we revealed that ethanol activates GIRK by shifting the conformational equilibrium processes, which are responsible for the gating of GIRK, to stabilize an open conformation of the cytoplasmic ion gate. We suggest that the dynamic molecular mechanism of the ethanol-induced activation of GIRK represents a general model of the ethanol action on signaling proteins in the human nervous system.
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