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

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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
StatePublished - Apr 1998

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Nicotinic Receptors
Bungarotoxins
Mutagenesis
Binding Sites
conotoxin MI
Mutation

ASJC Scopus subject areas

  • Pharmacology

Cite this

Sugiyama, N., Marchot, P., Kawanishi, C., Osaka, H., Molles, B., Sine, S. M., & Taylor, P. (1998). Residues at the subunit interfaces of the nicotinic acetylcholine receptor that contribute to α-conotoxin M1 binding. Molecular Pharmacology, 53(4), 787-794.

Residues at the subunit interfaces of the nicotinic acetylcholine receptor that contribute to α-conotoxin M1 binding. / Sugiyama, Naoya; Marchot, Pascale; Kawanishi, Chiaki; Osaka, Hitoshi; Molles, Brian; Sine, Steven M; Taylor, Palmer.

In: Molecular Pharmacology, Vol. 53, No. 4, 04.1998, p. 787-794.

Research output: Contribution to journalArticle

Sugiyama, N, Marchot, P, Kawanishi, C, Osaka, H, Molles, B, Sine, SM & Taylor, P 1998, 'Residues at the subunit interfaces of the nicotinic acetylcholine receptor that contribute to α-conotoxin M1 binding', Molecular Pharmacology, vol. 53, no. 4, pp. 787-794.
Sugiyama, Naoya ; Marchot, Pascale ; Kawanishi, Chiaki ; Osaka, Hitoshi ; Molles, Brian ; Sine, Steven M ; Taylor, Palmer. / Residues at the subunit interfaces of the nicotinic acetylcholine receptor that contribute to α-conotoxin M1 binding. In: Molecular Pharmacology. 1998 ; Vol. 53, No. 4. pp. 787-794.
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