ANTIBODIES TO SYNTHETIC PEPTIDES AS PROBES OF ACETYLCHOLINE-RECEPTOR STRUCTURE

Peptides containing the C-terminus of the .alpha.-chain of the nicotinic acetylcholine receptor (nAChR), as deduced from c[complementary]DNA data, were synthesized and shown to bind to antibodies to denatured nAChR. Peptide-specific antibodies bound to native and to denatured nAChR. Binding was exclusively to the .alpha.-chain. Trypsinization experiments and the use of the unique C-terminal hexapeptide of the .alpha.-chain demonstrated that the proposed C-terminus does exist on the mature .alpha.-chain, and that post-translational cleavage can be discounted as an explanation of the discrepancy of the molecular masses of the .alpha.-chain deduced from SDS [sodium dodecyl sulfate] gel electrophoresis (40 kDa) and from the DNA sequencing (50 kDa). Cleavage of the .alpha.-chain in the membrane occurs at 2 closely linked sites, resulting in the formation of a large fragment (.apprx. 35 kDa) and the remainder of the chain (.apprx. 9-10 kDa). No signs of experimental myasthenia gravis were observed in rabbits immunized with C-terminal peptide coupled to carrier protein.