Disruption of an intersubunit electrostatic bond is a critical step in glycine receptor activation.
Proper regulation of neurotransmission requires that ligand-activated ion channels remain closed until agonist binds. How channels then open remains poorly understood. Glycine receptor (GlyR) gating is initiated by agonist binding at interfaces between adjacent subunits in the extracellular domain. Aspartate-97, located at the alpha1 GlyR interface, is a conserved residue in the cys-loop receptor superfamily. The mutation of D97 to arginine (D97R) causes spontaneous channel opening, with open and closed dwell times similar to those of maximally activated WT GlyR. Using a model of the N-terminal domain of the alpha1 GlyR, we hypothesized that an arginine-119 residue was forming intersubunit electrostatic bonds with D97. The D97R/R119E charge reversal restored this interaction, stabilizing channels in their closed states. Cysteine substitution shows that this link occurs between adjacent subunits. This intersubunit electrostatic interaction among GlyR subunits thus contributes to the stabilization of the closed channel state, and its disruption represents a critical step in GlyR activation.
Todorovic
Jelena
J
Division of Pharmacology and Toxicology, Section of Neurobiology, Waggoner Center for Alcohol and Addiction Research and Institutes for Neuroscience and Cell and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA.
Welsh
Brian T
BT
Bertaccini
Edward J
EJ
Trudell
James R
JR
Mihic
S John
SJ
D000595:Amino Acid Sequence; D000818:Animals; D001120:Arginine / Q000378:metabolism; D001224:Aspartic Acid / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D018076:DNA, Complementary / Q000235:genetics; D004594:Electrophysiology; D015640:Ion Channel Gating / Q000502:physiology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D018408:Patch-Clamp Techniques; D018009:Receptors, Glycine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D055672:Static Electricity; D009435:Synaptic Transmission / Q000502:physiology*; D014981:Xenopus
D018076:DNA, Complementary; D018009:Receptors, Glycine; D001224:Aspartic Acid; D001120:Arginine
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