Mapping of the polypeptide chain organization of the main extracellular domain of the alpha-subunit in membrane-bound acetylcholine receptor by antipeptide antibodies spanning the entire domain.

Abstract

To study the organization of the polypeptide chain of the main extracellular domain of the nicotinic acetylcholine receptor (AChR) alpha-subunit, we examined the ability of the native membrane-bound AChR of Torpedo californica (T-AChR) to bind a panel of antibodies against overlapping synthetic peptides which collectively encompassed this entire domain. Antibodies against the alpha-chain peptides alpha 1-16, alpha 89-104 and alpha 158-174 were able to bind to membrane-bound T-AChR. Other anti-peptide antibodies showed little or no binding to T-AChR in the membrane. It is concluded that regions alpha 1-16, alpha 89-104 and alpha 158-174 are highly exposed on the surface of the alpha subunit of membrane-bound AChR.