Characterization of the deg-3/des-2 receptor: a nicotinic acetylcholine receptor that mutates to cause neuronal degeneration. 
The nicotinic acetylcholine receptor family (nAChR) is a large family of acetylcholine-gated cation channels.  Here we characterize the Caenorhabditis elegans DEG-3/DES-2 nAChR, a receptor identified due to its involvement in neuronal degeneration.  Pharmacological analysis of a DEG-3/DES-2 receptor expressed in Xenopus oocytes shows that this receptor is preferentially activated by choline.  This choline sensitivity of the DEG-3/DES-2 channel can explain its role in neuronal degeneration, as shown by the toxic effects of choline on oocytes expressing the mutant DEG-3/DES-2 channel.  We also show that in C. elegans the DEG-3/DES-2 receptor is localized to nonsynaptic regions, including the sensory endings of chemosensory neurons.  This localization is in agreement with a role for this receptor in chemosensation of choline, as inferred from a defect in chemotaxis for choline seen in deg-3 mutants.  Thus, this work also provides evidence for the diversity of nonsynaptic activities associated with nAChRs.