title: Synthetic peptides used to locate the alpha-bungarotoxin binding site and immunogenic regions on alpha subunits of the nicotinic acetylcholine receptor.
abstract: Synthetic peptides corresponding to 57% of the sequence of alpha subunits of acetylcholine receptors from Torpedo californica electric organ and extending from the NH2 to the COOCH terminus have been synthesized. The alpha-bungarotoxin binding site on denatured alpha subunits was mapped within the sequence alpha 185-199 by assaying binding of 125I-alpha-bungarotoxin to slot blots of synthetic peptides. Further studies showed that residues in the sequence alpha 190-194, especially cysteines-alpha 192, 193, were critical for binding alpha-bungarotoxin. Reduction and alkylation studies suggested that these cysteines must be disulfide linked for alpha-bungarotoxin to bind. Binding sites for serum antibodies to native receptors or alpha subunits were mapped by indirect immunoprecipitation of 125I-peptides. Several antigenic sequences were identified, but a synthetic peptide corresponding to the main immunogenic region (which is highly conformation dependent) was not identified.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D000936:Antigen-Antibody Complex / Q000032:analysis; D002038:Bungarotoxins / Q000378:metabolism*; D004557:Electric Organ / Q000378:metabolism*; D000939:Epitopes / Q000032:analysis; D046911:Macromolecular Substances; D010455:Peptides / Q000138:chemical synthesis; D011950:Receptors, Cholinergic / Q000378:metabolism*; D011978:Receptors, Nicotinic / Q000276:immunology / Q000378:metabolism*; D014101:Torpedo; D064569:alpha7 Nicotinic Acetylcholine Receptor
chemical_list: D000906:Antibodies; D000936:Antigen-Antibody Complex; D002038:Bungarotoxins; D000939:Epitopes; D046911:Macromolecular Substances; D010455:Peptides; D011950:Receptors, Cholinergic; D011978:Receptors, Nicotinic; D064569:alpha7 Nicotinic Acetylcholine Receptor