Family

Cation/H+ exchanger, CPA1 family, bacteria (IPR004705)

Short name: Cation/H_exchanger_CPA1_bac

Family relationships

Description

Sodium proton exchangers (NHEs) constitute a large family of integral membrane protein transporters that are responsible for the counter-transport of protons and sodium ions across lipid bilayers [PMID: 12027219, PMID: 12502567]. These proteins are found in organisms across all domains of life. In archaea, bacteria, yeast and plants, these exchangers provide increased salt tolerance by removing sodium in exchanger for extracellular protons. In mammals they participate in the regulation of cell pH, volume, and intracellular sodium concentration, as well as for the reabsorption of NaCl across renal, intestinal, and other epithelia [PMID: 16734752, PMID: 17071327, PMID: 16513813, PMID: 11187762]. Human NHE is also involved in heart disease, cell growth and in cell differentiation [PMID: 17218973]. The removal of intracellular protons in exchange for extracellular sodium effectively eliminates excess acid from actively metabolising cells. In mammalian cells, NHE activity is found in both the plasma membrane and inner mitochondrial membrane. To date, nine mammalian isoforms have been identified (designated NHE1-NHE9) [PMID: 9278382, PMID: 9507001]. These exchangers are highly-regulated (glyco)phosphoproteins, which, based on their primary structure, appear to contain 10-12 membrane-spanning regions (M) at the N terminus and a large cytoplasmic region at the C terminus. The transmembrane regions M3-M12 share identity with other members of the family. The M6 and M7 regions are highly conserved. Thus, this is thought to be the region that is involved in the transport of sodium and hydrogen ions. The cytoplasmic region has little similarity throughout the family. There is some evidence that the exchangers may exist in the cell membrane as homodimers, but little is currently known about the mechanism of their antiport [PMID: 9537504].

This entry represents bacterial Na+/H+ exchanger proteins such as YjcE from Escherichia coli [PMID: 11700351].

GO terms

Biological Process

GO:0006812 cation transport

Molecular Function

GO:0015299 solute:proton antiporter activity

Cellular Component

GO:0016021 integral component of membrane

Contributing signatures

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