Alternative splicing of gar-1, a Caenorhabditis elegans G-protein-linked acetylcholine receptor gene

We have recently identified a gene, designated gar-1, coding for a novel form of G-protein-linked acetylcholine (ACh) receptor in Caenorhabditis elegans. Although this receptor is most closely related to muscarinic ACh receptors (mAChRs), electrophysiological analyses have shown that ligand binding specificity of the receptor is distinct from that of mAChRs. Here we report that three receptor isoforms are generated by alternative splicing of the gar-1 transcript. These receptor isoforms differ only in the third intracellular loop that is considered to be important for G protein coupling. The three splice variants, when expressed in Xenopus oocyte, displayed similar pharmacological profiles and signaling activities. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis showed that the three gar-1 mRNAs are present at all developmental stages examined. The results in this study provide evidence that alternative splicing is involved in promoting molecular diversity of G-protein-linked ACh receptors.