Epithelial sodium channel

This MedLibrary.org supplementary page on Epithelial sodium channel is provided directly from the open source Wikipedia as a service to our readers. Please see the note below on authorship of this content, as well as the Wikipedia usage guidelines. To search for other content from our encyclopedia supplement, please use the form below:

Related Sponsors

BM Pharmacy Generic pharmaceuticals at unbeatable prices. Insomnia, men's health, hair health, pain control. bmpharmacy.com
Online Pharmacy Carisoprodol, tadalafil, sildenafil, vardenafil and more... xlpharmacy.com
MedBasket.com Discreet. Inexpensive. Fast shipping. Great selection. What more can we say? medbasket.com
Frugalmed 2000 reasons to shop with us first. frugalmed.com
Ads by Tiva

schematic picture of an ENaC
schematic picture of an ENaC

The epithelial sodium channel (short: ENaC, also: sodium channel non-neuronal 1 (SCNN1) or amiloride sensitive sodium channel (ASSC)) is a membrane-bound ion-channel that is permeable for Li+-ions, protons and especially Na+-ions. It is a constitutively active ion-channel. It is arguably the most selective ion channel.

Contents

Structure

ENaC consists of three different subunits: α, β, γ. The stoichometry of these subunits is still to be verified, but ENaC is very likely to be a heterotrimeric protein like the recently analyzed acid-sensing ion channel 1 (ASIC1), which belongs to the same family.[1] Each of the subunits consists of two transmembrane helices and an extracellular loop. The amino- and carboxy-termini of all polypeptides are located in the cytosol.

Location and function

ENaC is located in the apical membrane of polarized epithelial cells particularly in the kidney, the lung and the colon. It is involved in the transepithelial Na+-ion transport which it accomplishes together with the Na+/K+-ATPase.

It plays a major role in the Na+- and K+-ion homeostasis of blood, epithelia and extraepithelial fluids by resorption of Na+-ions. The activity of ENaC in colon and kidney is modulated by the mineralcorticoid aldosterone. It can be blocked by either triamterene or amiloride, which are used medically to serve as diuretics.

ENaC can furthermore be found in taste receptor cells, where it plays an important role in salt taste perception. In rodents virtually the entire salt taste is mediated by ENaC, whereas it seems to play a less significant role in humans: about 20 percent can be accredited to the epithelial sodium channel.

δ-subunit

In addition there is a fourth, so-called δ-subunit, that shares considerable sequence similarity with the α-subunit and can form a functional ion-channel together with the β- and γ-subunits. Such δ, β, γ-ENaC appears in pancreas, testes and ovaries. Their function is yet unknown.

Clinical significance

Units β and γ are associated with Liddle's syndrome.[2]

Amiloride and triamterene are potassium-sparing diuretics which act upon the Epithelial sodium channel.

Genes

References

  1. ^ Jasti J, Furukawa H, Gonzales EB, Gouaux E (2007). "Structure of acid-sensing ion channel 1 at 1.9 Å resolution and low pH". Nature 449: 316–322. doi:10.1038/nature06163. 
  2. ^ Ion Channel Diseases

External links

v • d • e
Membrane transport protein: ion channels
Ca2+: Calcium channel
L-type/Cavα (1.1, 1.2, 1.3, 1.4) • N-type/Cavα2.2 • P-type/Cavα(2.1) • Q-type/Cavα2.1 • R-type/Cavα2.3 • T-type/Cavα(3.2)
α2δ-subunits (1, 2) • β-subunits (β1, β2, β3, β4) • γ-subunits (γ1, γ2, γ3, γ4)
Other
Na+: Sodium channel
Navα (1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 7A) • Navβ (1, 2, 3, 4)
Other
Epithelial sodium channel (α, β, γ, δ)
K+: Potassium channel
Kvα (1-6) (1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.10, 2.1, 2.2, 3.1, 3.2, 3.3, 3.4, 4.1, 4.2, 4.3, 5.1, 6.1, 6.2, 6.3, 6.4)
Kvα (7-12) (7.1, 7.2, 7.3, 7.4, 7.5, 8.1, 8.2, 9.1, 9.2, 9.3, 10.1, 10.2, 11.1/hERG, 11.2, 11.3, 12.1, 12.2, 12.3)
Kvβ (1, 2, 3) • KCNIP (1, 2, 3, 4) • minK/ISK • MiRP (1, 2, 3) • Shaker gene
Kir (1.1, 2.1, 2.2, 2.3, 2.4) • GIRK/Kir (3.1, 3.2, 3.3, 3.4) • Kir (4.1, 4.2, 5.1, 6.1, 6.2, 7.1)
K2P (1, 2, 3, 4, 5, 6, 7, 9, 10, 12, 13, 15, 16, 17, 18)
M+: TRP cation channel
TRPA (1) • TRPC (1, 2, 3, 4, 4AP, 5, 6, 7) • TRPM (1, 2, 3, 4, 5, 6, 7, 8) • TRPML (1, 2, 3) • TRPP (1, 2) • TRPV (1, 2, 3, 4, 5, 6)
Cl-: Chloride channel
CFTR • CLCA (1, 2, 3, 4) • CLCN (1, 2, 3, 4, 5, 6, 7, KA, KB) • CLIC (1, 2, 3, 4, 5, 6) • CLNS (1A, 1B)
Cyclic nucleotide-gated
α1, α2, α3, α4, β1, β3, H1, H2, H3, H4
Porin
Other/general

Wikipedia content modification information:

  • This page was last modified on 13 July 2008, at 12:08.

Wikipedia Authorship and Review

Wikipedia content provided here is not reviewed directly by MedLibrary.org. Wikipedia content is authored by an open community of volunteers and is not produced by or in any way affiliated with MedLibrary.org.

Wikipedia Usage Guidelines

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article on "Epithelial sodium channel".

The URL for this specific entry is:

All Wikipedia text is available under the terms of the GNU Free Documentation License. (See Copyrights for details). Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc.