The Na-K-Cl cotransporters are a family of integral membrane proteins that mediate the coupled transport of Na+, K+, and Cl- across the plasma membrane.NKCC2 protein is encoded in 26 exons, and the coding region spans 80 kb of genomic DNA with introns that range in length from 120 bp to 15 kb. The location of intron/exon boundaries are very similar to those seen in SLC10A3 through exon 19. Three alternative forms of exon 4 are encoded in genomic DNA, as reported in other species.The gene, symbolized SLC12A1 in human and mouse, is structurally related to another Na-K-Cl cotransporter (SLC12A2; previously called NKCC1) which, unlike the kidney-specific SLC12A1, is expressed in many tissues, including the basolateral membrane of secretory epithelia, where it mediates active chloride secretion.