Epithelial sodium channel

The epithelial sodium channel (short: ENaC by engl:. .. Epithelial Na channel; well SCNN1 of engl: sodium channel non- neuronal 1 or ASSC of engl: amiloride -sensitive sodium channel ) is a membrane-bound ion channel, in addition to Li ions and protons is permeable mainly for Na ions. It is open in the ground state, one speaks of a constitutively active channel.

The epithelial sodium channel is composed of three subunits ( α, β, γ ), which are probably set up to a heterotrimer. Each of the three subunits has two transmembrane helices and an extracellular loop. The amino and carboxy termini of the polypeptide chains are located in the cytosol.

Mutations in the genes encoding for ENaC subunits can Pseudohypoaldosteronism type 1 ( α, β ), and Liddle syndrome ( β, γ ) cause.

Until recently it was assumed that ENaC is a heterotetramer, however, provided the structure elucidation of the "acid - sensing ion channels 1" ( ASIC1 ) reasons to question this assumption. The elucidation of this related ion channel had in fact shown that this is designed as a heterotrimer.

ENaC located in the apical membranes of epithelial polar primarily in the kidney, lung and colon (colon ). He is involved in the transepithelial transport of Na ions, which he accomplished together with the Na / K -ATPase. It plays an important role in maintaining the Na and K concentrations in blood, epithelia and extraepithelialen liquids by reabsorbed Na ions from primary urine and intestinal lumen. The ENaC activity and expression in the kidney and colon is modulated by the mineralocorticoid aldosterone. ENaC can be blocked by amiloride. This property makes you look in the medicine such as by employing as a diuretic amiloride.

Furthermore, ENaC is present in taste receptor cells. Here he plays an important role in the perception of salt taste. While in rodents almost all of the salty taste is mediated by ENaC, in humans caused only about a fifth of the perception on ENaC.

There is a further so-called δ - subunit, which has high homology to the α - subunit and can replace these with the formation of a functional channel. Such δ, β, γ tetramers occur for example in the pancreas, testes or ovaries, but its function is still unclear.

Swell

  • Sensory Physiology
  • Taste
  • Membrane channel
  • Hereditary disease - associated protein
Protein isoform Liddle's syndrome Epithelium Sensory system Ovary UniProt Digital Object Identifier
310586
de