Quaternary structure and reconstitution of acetylcholine receptor from Torpedo Californica.
The nicotinic acetylcholine receptor (AChR) from Torpedo californica electric tissue is a protein complex of MW 270 000 consisting of a binding moiety (receptor) and an ion channel (effector). Reconstitution experiments present evidence that receptor and effector may be located on different subunits of the protein complex. The subunit composition of the membrane bound AChR complex is investigated by affinity labeling experiments and nearest neighbour analysis using cross-linking reagents. In addition to the four main polypeptides ?, ?, ?, ?, other minor components are present. Two ATP binding polypeptide chains (MW 45,000 and 55,000) and one chain reacting with an N(3)-derivative of cobra toxin (MW 55 000) were detected. Nearest neighbour analysis showed close proximity between two ? polypeptide chains and also between two ? chains. Furthermore the agonist and antagonist binding chain ? is located close to ?, ?, and ?, and ? is close to ? and ?.
Schiebler
W
W
Institut für Biochemie, Freie Universität Berlin, Berlin, Germany.
Bandini
G
G
Hucho
F
F