Disruption of an intersubunit electrostatic bond is a critical step in glycine receptor activation

Proc Natl Acad Sci U S A. 2010 Apr 27;107(17):7987-92. doi: 10.1073/pnas.1001845107. Epub 2010 Apr 12.

Abstract

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.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Arginine / metabolism
  • Aspartic Acid / genetics
  • Aspartic Acid / metabolism
  • Base Sequence
  • DNA, Complementary / genetics
  • Electrophysiology
  • Ion Channel Gating / physiology*
  • Models, Molecular*
  • Molecular Sequence Data
  • Mutation / genetics
  • Patch-Clamp Techniques
  • Receptors, Glycine / chemistry
  • Receptors, Glycine / genetics
  • Receptors, Glycine / metabolism*
  • Sequence Analysis, DNA
  • Static Electricity
  • Synaptic Transmission / physiology*
  • Xenopus

Substances

  • DNA, Complementary
  • Receptors, Glycine
  • Aspartic Acid
  • Arginine