Purified acetylcholine receptor: its reconstitution to a chemically excitable membrane.

Association of purified acetylcholine receptor from Torpedo californica electroplax with lipids from the same organism results in a vesicular membrane system in which the receptor protein is oriented so that all neurotoxin binding sites appear to be on the outer surface. The reconstituted system is chemically excitable by acetylcholine and carbamylcholine, as measured by (22)Na(+) efflux. This excitability is specifically blocked by the antagonist alpha-bungarotoxin. These results demonstrate that the purified receptor macromolecule contains not only the specific neurotransmitter binding site but also the molecular elements necessary for ion translocation in order to effect postsynaptic depolarization.