Biosynthesis of acetylcholine receptor in vitro.

Torpedo acetylcholine receptor is accessible to analysis by cell-free protein synthesis, like other membrane proteins studied previously. The factors deserving particular attention in this system are the small amounts of messenger RNA contained in electroplax tissue, the inherent complexity of an oligomeric membrane protein (necessitating the use of subunit-specific antibodies), the anomalous electrophoretic behavior of the primary translation products (attributable in part to the high--SH content of sAChRs), and the multiple glycosylated forms that appear upon processing by microsomal membranes. Although not all these complexities can be satisfactorily explained, they have been empirically characterized and can be well controlled if the appropriate procedures are followed.