Isolation and Characterization of Na+/Ca2+ Exchanger Gene and Splicing Isoforrns in Mice

The Na+/Ca2+ exchanger gene NCXl is ubiquitously expressed in mammalian tissues, and encodes several isoforms through alternative RNA splicing. In this report, we describe the gene structure that gives rise to the multiple isoforms, and the tissue-specific expression of these isoforms in mice. The mouse NCXl gene contains a cluster of six exons (A, B, C, D, E, and F) which encode a variable region in the large intracellular loop of the protein, as previously reported in rabbits and humans. Using reverse tran-scription-polymerase chain reaction (RT-PCR), expression of the isoforms was examined in several tissues. We also identified a novel splice variant, which originate from exons A, C, D, and F. These findings provide new insights into the significance of the large repertoire of NCXl isoforms.