Sodium–hydrogen antiporter 3 also known as sodium–hydrogen exchanger 3 (NHE3) or solute carrier family 9 member 3 (SLC9A3) is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
that in humans is encoded by the ''SLC9A3''
gene
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...
.
SLC9A3 is a
sodium–hydrogen antiporter. It is found on the apical side of the
epithelial cells of the proximal tubule of the
nephron
The nephron is the minute or microscopic structural and functional unit of the kidney. It is composed of a renal corpuscle and a renal tubule. The renal corpuscle consists of a tuft of capillaries called a glomerulus and a cup-shaped structu ...
of the
kidney
In humans, the kidneys are two reddish-brown bean-shaped blood-filtering organ (anatomy), organs that are a multilobar, multipapillary form of mammalian kidneys, usually without signs of external lobulation. They are located on the left and rig ...
, in the
apical membrane of
enterocytes of the
intestine, as well as the basolateral side of both duodenal and pancreatic cells responsible for the release of bicarbonate into the duodenal lumen. It is primarily responsible for maintaining the balance of
sodium
Sodium is a chemical element; it has Symbol (chemistry), symbol Na (from Neo-Latin ) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the peri ...
. It is also indirectly linked to buffering of blood pH. The NHE3 antiporter imports one sodium ion into the cytosol of a tubule cell as it ejects one hydrogen ion from the cell into the lumen of the proximal tubule. The sodium within the tubule cell may then be retained by the body rather than excreted in the urine. The NHE3 antiporter indirectly contributes to blood buffering capacity because hydrogen ions that are ejected are the products of the carbonic anhydrase enzyme, which also makes bicarbonate.
VI. Mechanisms of Salt & Water Reabsorption
Regulation
Protein kinase C stimulates NHE3, while protein kinase A inhibits it.[852 Page 852]
There is a specific protein functioning as an NHE3 regulator, Sodium-hydrogen antiporter 3 regulator 1.
Inhibitors
* Tenapanor
Stimulators
* Insulin
Insulin (, from Latin ''insula'', 'island') is a peptide hormone produced by beta cells of the pancreatic islets encoded in humans by the insulin (''INS)'' gene. It is the main Anabolism, anabolic hormone of the body. It regulates the metabol ...
Interactions
Sodium–hydrogen antiporter 3 has been shown to interact with CHP.
References
Further reading
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External links
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Solute carrier family
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