Sodium/calcium exchanger, isoform 1 (IPR002987)

Short name: NaCa_exhngr1

Overlapping homologous superfamilies


Family relationships


Na+/Ca2+ exchange proteins are involved in maintaining Ca2+ homeostasis in a wide variety of cell types. They are found in both the plasma membrane and intracellular organellar membranes, where they exchange Na+ for Ca2+ in an electrogenic manner. When located in the plasma membrane, they generally utilise the transmembrane (TM) Na+ concentration gradient in order to extrude Ca2+ from cells. Three mammalian isoforms have been cloned to date (NCX1-3), which consist of 920-970 amino acid residues that are predicted to possess 11 or 12 TM domains. Interestingly, they possess a short motif (~30 residues) that is similar to the Na+/K+-ATPase, although its function is unknown [PMID: 1700476, PMID: 8798769].

NCX1 is the principal Na+/Ca2+ exchanger of cardiac myocytes, where it is thought to play an important role in excitation-contraction coupling. It is also found in a variety of other tissues, suggesting it serves as a housekeeping protein, maintaining low cytosolic Ca2+ concentration. Alternatively spliced variants of NCX1 have been identified, expression of which is cell type-specific. Sequence analysis reveals two sets of tandem repeats are found within the NCX1 protein sequence, which are usually referred to as alpha and beta. The alpha repeats are thought to be involved in the ion binding and translocation reactions of the exchanger, and the first beta repeat may be part of a regulatory site that responds to Ca2+ concentration.

GO terms

Biological Process

GO:0006816 calcium ion transport

Molecular Function

GO:0005432 calcium:sodium antiporter activity

Cellular Component

GO:0016020 membrane

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.