Adult thymus expresses an embryonic nicotinic acetylcholine receptor-like protein

The subunit composition of acetylcholine receptor-like protein(s) (AChR-LP) expressed by normal thymus was investigated. In skeletal muscle, the AChR exists in two forms, an embryonic form which contains the gamma-subunit and an adult form where the gamma-subunit is substituted by a different, homologous subunit called epsilon. Antibodies against unique sequence segments of the embryonic gamma-subunit and of the adult epsilon-subunit of bovine muscle AChR, in addition to antibodies specific for the alpha-, beta-, and delta-subunits of bovine muscle AChR, were used to probe immunoblots of AChR-LP(s) from bovine thymus. Subunits of approximate Mr 41 kDa, 48-54 kDa, 57 kDa and 67-72 kDa were recognized by anti-alpha, anti-beta, anti-gamma and anti-delta antibodies respectively. Anti-epsilon antibodies did not recognize any protein band from bovine thymus. AChR-LP similar or identical to the embryonic muscle AChR is therefore expressed in normal thymus.