NCKX1, also designated solute carrier family 24, member 1 (SLC24A1) or sodium/calcium/potassium exchanger 1, belongs to a family of potassium-dependent sodium/calcium exchangers. Members of this group of proteins contain two large hydrophilic loops and two sets of multiple transmembrane-spanning segments. One intron in the 5' untranslated region and eight within the coding region of the NCKX1 gene have been identified; exon length varies from 54 to 2,037 bp. Human NCKX1 encodes a protein of 1,081 amino acids that shows 64% overall identity with the cow protein. The two sets of presumed transmembrane domains and their short connecting loops show 94% identity with that of the cow, while the extracellular loop at the amino terminus is only 59% identical.