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

To study the organization of the polypeptide chain of the main extracellular domain of the nicotinic acetylcholine receptor (AChR) α- 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 α-chain peptides α1-16, α89-104 and α158-174 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 α1-16, α89-104 and α158-174 are highly exposed on the surface of the α subunit of membrane-bound AChR.