Differential surface accessibility of α(187-199) in the torpedo acetylcholine receptor α subunits

Robert H Fairclough, George M. Twaddle, Eswari Gudipati, Mike Y. Lin, David P Richman

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

We have probed the surface accessibility of residues α187 to α199 of the Torpedo acetylcholine receptor with monoclonal antibody 383C, which binds uniquely to these residues. However, 383C binds to only one of the two α subunits in the membrane-bound receptor, neither of the two subunits in carbamylcholine-desensitized receptor, and to both α subunits in Triton X-100 solubilized receptor. The kinetics of association and dissociation of 383C with the peptide α(183-199) compared to those with the membrane-bound receptor suggest that all but a single hydrogen bond of affinity derives from contacts between this peptide and the monoclonal antibody paratope. Inhibition of 383C binding by α-bungarotoxin selectively directed to the α subunit correlated with the high-affinity d-tubocurarine binding site, along with a lack of inhibition by α-bungarotoxin directed to the α subunit correlated with the low-affinity d-tubocurarine binding site, suggests that the 383C epitope on the membrane-bound receptor resides on the α subunit associated with the high-affinity d-tubocurarine binding site. The results presented here suggest a structural basis for the differences between the two receptor acetylcholine binding sites.

Original languageEnglish (US)
Pages (from-to)317-330
Number of pages14
JournalJournal of Molecular Biology
Volume282
Issue number2
DOIs
StatePublished - Sep 18 1998

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Keywords

  • α-bungarotoxin binding sites
  • Acetylcholine binding sites
  • Acetylcholine receptor
  • Anti-acetylcholine receptor monoclonal antibody
  • d-tubocurarine binding sites

ASJC Scopus subject areas

  • Virology

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