Residues at the subunit interfaces of the nicotinic acetylcholine receptor that contribute to α-conotoxin M1 binding

Naoya Sugiyama, Pascale Marchot, Chiaki Kawanishi, Hitoshi Osaka, Brian Molles, Steven M. Sine, Palmer Taylor

Research output: Contribution to journalArticle

42 Scopus citations

Abstract

The two binding sites in the pentameric nicotinic acetylcholine receptor of subunit composition α2βγδ are formed by nonequivalent α-γ and α- δ subunit interfaces, which produce site selectivity in the binding of agonists and antagonists. We show by sedimentation analysis that 125I-α- conotoxin M1 binds with high affinity to the α-δ subunit dimers, but not to α-γ dimers, nor to α, γ, and δ monomers, a finding consistent with α- conotoxin M1 selectivity for the αδ interface in the intact receptor measured by competition against α-bungarotoxin binding. We also extend previous identification of α-conotoxin M1 determinants in the γ and δ subunits to the α subunit interface by mutagenesis of conserved residues in the α subunit. Most mutations of the α subunit affect affinity similarly at the two sites, but Tyr93Phe, Val188Lys, Tyr190Thr, Tyr198Thr, and Asp152Asn affect affinity in a site-selective manner. Mutant cycle analysis reveals only weak or no interactions between mutant a and non-α subunits, indicating that side chains of the α subunit do not interact with those of the γ or δ subunits in stabilizing α-conotoxin M1. The overall findings suggest different binding configurations of α-conotoxin M1 at the α-δ and α-γ binding interfaces.

Original languageEnglish (US)
Pages (from-to)787-794
Number of pages8
JournalMolecular pharmacology
Volume53
Issue number4
DOIs
StatePublished - Apr 1998

ASJC Scopus subject areas

  • Molecular Medicine
  • Pharmacology

Fingerprint Dive into the research topics of 'Residues at the subunit interfaces of the nicotinic acetylcholine receptor that contribute to α-conotoxin M1 binding'. Together they form a unique fingerprint.

  • Cite this