Segment α 182‐198 of Torpedo californica acetylcholine receptor contains a second toxin‐binding region and binds anti‐receptor antibodies

Abstract
The area around Cys-192 and Cys-193 is thought to be a functionally important part of the α-subunit of the acetylcholine receptor. We have synthesized peptide α 182-198 of the α-chain of the Torpedo californica acetylcholine receptor and investigated the binding to the peptide of α-bungarotoxin, cobratoxin and antibodies raised against acetylcholine receptor. The results showed that the synthetic peptide α 182-198 contains a second toxin-binding region and also binds a considerable fraction of anti-receptor antibodies. We also report here the toxin-binding activity of synthetic peptide a 125–148 of the human acetylcholine receptor which has been previously localized as a toxin-binding region in the α-chain of the Torpedo receptor.