Electrogenic Sodium Bicarbonate Cotransporter 2 (NBC2)

The deduced 1,018-amino acid NBC2 protein has 10 predicted transmembrane domains, with the N and C termini located in the cytosol; a cluster of 5 potential N-linked glycosylation sites; consensus sites for protein kinase A, protein kinase C, and casein kinase; and a stretch of 15 highly hydrophilic amino acids at the C terminus. The NBC2 protein shares 53% sequence identity with the kNBC variant of NBC1 (SLC4A4) and 38% identity with AE1. Northern blot analysis of human mRNAs detected an 8.5-kb SLC4A7 transcript in several tissues, including testis, spleen, ovary, small intestine, colon, thymus, heart, and muscle; expression was not found in pancreas or liver. Analysis of rat tissues showed that Slc4a7 is expressed predominantly in the retina.