Inhibition of the ethanol-induced potentiation of α1 glycine receptor by a small peptide that interferes with Gβγ binding

Abstract

Previous studies indicate that ethanol can modulate glycine receptors (GlyR), in part, through Gβγ interaction with basic residues in the intracellular loop. In this study, we show that a seven-amino acid peptide (RQHC7), which has the primary structure of a motif in the large intracellular loop of GlyR (GlyRIL), was able to inhibit the ethanol-elicited potentiation of this channel from 47 ± 2 to 16 ± 4%, without interfering with the effect of Gβγ on GIRK (G protein activated inwardly rectifying potassium channel) activation. RQHC7 displayed a concentration-dependent effect on ethanol action in evoked and synaptic currents. A fragment of GlyR-IL without the basic amino acids did not interact with Gβγ or inhibit ethanol potentiation of GlyR. In silico analysis using docking and molecular dynamics allowed to identify a region of ∼350Å2 involving aspartic acids 186, 228, and 246 in Gβγ where we propose that RQHC7 binds and exerts its blocking action on the effect of ethanol in GlyR. © 2012 by The American Society for Biochemistry and Molecular Biology, Inc.