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 fo rm of G-protein-linked acetylcholine (ACh) receptor in Caenorhabditis elega ns, Although this receptor is most closely related to muscarinic ACh recept ors (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 intracel lular loop that is considered to be important for G protein coupling. The t hree splice variants, when expressed in Xenopus oocyte, displayed similar p harmacological profiles and signaling activities, Reverse transcriptase-pol ymerase 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 molecu lar diversity of G-protein-linked ACh receptors. (C) 2000 Academic Press.