Isolation of acetylcholine receptor-like protein from fetal calf thymus.

Cobrotoxin-binding protein from fetal calf thymus was isolated by affinity chromatography after solubilization with Triton X-100 or sodium cholate. Its specificity as a nicotinic acetylcholine receptor (AChR) was determined by assessing the binding to radiolabeled alpha-bungarotoxin (BuTx) and to serum containing antibody against AChR obtained from a patient with myasthenia gravis (MG). AChR-like protein was detected in the amount of 0.41 -2.04 X 10(-9) mol alpha-BuTx binding sites per g protein. Polyacrylamide gel electrophoresis in sodium dedecylsulfate (SDS) revealed polypeptide bands with molecular weights of 40,000, 46,000, 55,000, 70,000, 35,000, and 26,000 daltons. As this protein may play an important role in immunopathological changes in MG, related studies are underway.