Although the nicotinic acetylcholine receptors (nAChRs) are the best characterized ionotropic neurotransmitter receptors, the extent of the molecular and functional diversity of the nAChR gene family is not known for a single organism. A number of C. elegans nAChR subunit genes have been identified previously using genetic approaches [
lev-1(non-a),
unc-38(a),
unc-29(non-a),
deg-3(a)] and cross-species probing of C. elegans cDNA libraries [
acr-2(non-a),
acr-3(non-a),and Ce-21(a)]. nAChR a-subunits may be distinguished from all other ionotropic receptor subunits by the presence of adjacent cysteines at positions equivalent to 192,193 in the Torpedo a-subunit. We have applied an RT-PCR strategy to confirm the expression of 8 novel putative nAChR a-subunits predicted by GENEFINDER. Analysis of the regions of the a-subunit considered to (a) contribute to the acetylcholine binding site and (b) the channel lining, has revealed a diversity which may underlie distinct functional roles for members of this multi-gene family.