Sodium/calcium exchanger protein (IPR004836)

Short name: Na_Ca_Ex

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 has been found to be predominantly expressed in the heart, where it plays an important role in excitation-contraction coupling, but it is also abundant in a variety of other tissues [PMID: 1700476]. NCX2 and NCX3 transcripts have been detected in the brain and skeletal muscle [PMID: 8798769, PMID: 8021246]. Homologous Na+/Ca2+ exchange proteins have also been found in Caenorhabditis elegans, Drosophila melanogaster and Loligo opalescens (California market squid).

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.