Cloning, characterization and chromosomal assignment of NBC4, a new member of the sodium bicarbonate cotransporter family

We report the cloning, characterization and chromosomal assignment of a new member of the sodium bicarbonate cotransporter (NBC) family, NBC4, from human heart. NBC4 maps to chromosome 2p13 and is a new candidate gene for Alstrom syndrome. NBC4 encodes a 1074-residue polypeptide with 12 putative membrane-spanning domains. Unlike other members of the NBC family, NBC4 has a unique giycine-rich region (amino acids 438-485). In addition, NBC4 lacks the lysine-rich C-terminus ofNBC1 with which it is most homologous. The first of two putative stilbene binding motifs (K(M/L)(X)K) is lacking in NBC4 (amino acids 655-658). The similar to 6 kb NBC4 transcript is moderately expressed in heart, with the highest expression in liver, testes and spleen. O 2000 Elsevier Science B.V. All rights reserved.