Antigenic sites of the nicotinic acetylcholine receptor cannot be predicted from the hydrophilicity profile.

The amino acid sequences of the polypeptide chains of the acetylcholine receptor have recently been published. From the hydrophilicity profiles, it has been proposed that residues 161-166 of the alpha-chain might be an important antigenic site. We have synthesised a peptide containing this sequence and raised antisera to it. Here we report that this peptide does not represent an important antigenic site on the molecule, and that this region is probably inaccessible to antibodies. Based on the known DNA sequences and hydrophilicity profiles of the receptor chains, we suggest that many regions of high hydrophilicity may represent inter-domain regions of proteins.