The C.elegans ric-3 gene is required for maturation of nicotinic acetylcholine receptors

Mutations in ric‐3 ( r esistant to i nhibitors of c holinesterase) suppress the neuronal degenerations caused by a gain of function mutation in the Caenorhabditis elegans DEG‐3 acetylcholine receptor. RIC‐3 is a novel protein with two transmembrane domains and extensive coiled‐coil domains. It is expressed in both muscles and neurons, and the protein is concentrated within the cell bodies. We demonstrate that RIC‐3 is required for the function of at least four nicotinic acetylcholine receptors. However, GABA and glutamate receptors expressed in the same cells are unaffected. In ric‐3 mutants, the DEG‐3 receptor accumulates in the cell body instead of in the cell processes. Moreover, co‐expression of ric‐3 in Xenopus laevis oocytes enhances the activity of the C.elegans DEG‐3/DES‐2 and of the rat α‐7 acetylcholine receptors. Together, these data suggest that RIC‐3 is specifically required for the maturation of acetylcholine receptors.