Identification and Reconstitution of a Neuronal Acetylcholinereceptor from Insects

Abstract

The nicotinic acetylcholine receptor (AChR) which is involved in vertebrate neuromuscular transmision and the generation of electric impulses by electroplaques of fish has been extensively studied by electrophysiological, biochemical, structural and molecular approaches; it is now the best characterized membrane channel from exitable cells (Conti-Tronconi and Raftery, 1982; Maelicke, 1984; Popot and Changeux, 1984). Nicotinic AChRs, i.e. response to nicotine which is blocked by α-tubocurarine and is not mimicked by muscarinic agonists, have been detected electrophysiological in many areas in the brain. However, much less is known about molecular aspects of nicotinic receptors in nervous tissue. The neuronal AChR is supposed to be significantly different, since it was already established in classical pharmacological studies (Paton and Zaimis, 1951) that the nicotinic AChR of nervous tissue, e.g. sympathetic ganglia, is subtly different from the receptor at the neuromuscular junction and more recently it has been reported that α-bungarotoxin which binds specifically to muscle and electrocytes AChRs and which has proved to be the most important tool in nicotinic receptor analysis, failed to block the nicotinic function in neuronal preparations (Patrick and Stallup, 1977). Recently great efforts have been made to characterize the nicotinic receptor in the vertebrate brain (Morley and Kemp, 1981) and significant progress has been made (Conti-Tronconi et al., 1985; Boulter et al., 1986). Considering the difficulties to identify the AChR proteins from vertebrate brain, it was of interest, whether analysing the nicotinic receptors from nervous tissues of invertebrates may provide some valuable informations.