Evidence for three additional P2X2 purinoceptor isoforms produced by alternative splicing in the adult rat vestibular end-organs

P2X(2) receptors are ligand-gated ion channels that are activated by extracellular ATP. To characterize the expression of P2X(2) purinoceptor in the adult rat vestibular periphery, reverse transcription-polymerase chain reaction (RT-PCR) was used. No transcript for P2X(2) receptor was found in the vestibular primary efferent neurons (Scarpa's ganglia); however, partial cDNAs encoding four splice variants of the P2X(2) receptor were isolated from vestibular end-organs. In all four cDNAs, the deletions were of different lengths but started at the same position on the P2X(2) gene (Val-370 codon) located toward the intracellular carboxyl terminus. One of these receptor isoforms was identical in sequence to the recently published P2X(2(b)) receptor (Simon et al., 1997, Mol. Pharmacol. 52, 237-248) (also known as P2X(2-2), in the nomenclature of Brandle et al., 1997, FEES Lett. 404, 294-298). The remaining three novel splice variants of the P2X(2) receptor were designated P2X(2(e)), P2X(2(f)) and P2X(2(g)) (GenBank accession numbers AF028603, AF028604 and AF028605, respectively). The functional significance of these three splice variants remains to be determined. Pituitary and cerebellum were used as survey tissues and only the P2X(2(b)) receptor cDNA was found. (C) 1998 Published by Elsevier Science B.V. All rights reserved.