Summary: Sodium/hydrogen exchanger family
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Sodium/hydrogen exchanger family Provide feedback
Na/H antiporters are key transporters in maintaining the pH of actively metabolising cells. The molecular mechanisms of antiport are unclear. These antiporters contain 10-12 transmembrane regions (M) at the amino-terminus and a large cytoplasmic region at the carboxyl 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.
Internal database links
|Similarity to PfamA using HHSearch:||Na_H_antiport_1|
External database links
|Transporter classification:||2.A.36 2.A.37|
This tab holds annotation information from the InterPro database.
InterPro entry IPR006153
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 [PUBMED:12027219, PUBMED: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 [PUBMED:16734752, PUBMED:17071327, PUBMED:16513813, PUBMED:11187762]. Human NHE is also involved in heart disease, cell growth and in cell differentiation [PUBMED: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) [PUBMED:9278382, PUBMED: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 [PUBMED:9537504].
This entry represents a number of cation/proton exchangers, including Na+/H+ exchangers, K+/H+ exchangers and Na+(K+,Li+,Rb+)/H+ exchangers.
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Cellular component||integral to membrane (GO:0016021)|
|Molecular function||solute:hydrogen antiporter activity (GO:0015299)|
|Biological process||transmembrane transport (GO:0055085)|
|cation transport (GO:0006812)|
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Curation and family details
|Seed source:||Pfam-B_312 (release 3.0)|
|Author:||Finn RD, Bateman A|
|Number in seed:||80|
|Number in full:||17250|
|Average length of the domain:||371.20 aa|
|Average identity of full alignment:||18 %|
|Average coverage of the sequence by the domain:||66.67 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||16|
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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the Na_H_Exchanger domain has been found. There are 5 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.
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