Nicotinic acetylcholine receptors have ligand-specific attachment point patterns.

Employing a panel of synthetic peptides as representative structural elements of the nicotinic acetylcholine receptor from Torpedo electric organ, we recently identified three sequence regions of the receptor (alpha 55-74, alpha 134-153 and alpha 181-200) serving as subsites for the binding of high molecular weight antagonists of acetylcholine (Conti-Tronconi et al. 1990). The relative binding affinities to these subsites of alpha-bungarotoxin and three competitive antibodies varied in a ligand-specific fashion. Employing a set of homologous synthetic peptides differing from alpha 181-200 by the exchange of single amino acid residues along the sequence, we now find that ligand binding cruci…