PROSITE documentation PDOC00926
Amiloride-sensitive sodium channels signature


Amiloride-sensitive sodium channels (ASC) [1,2,3] are sodium permeable non-voltage-sensitive ion channels inhibited by the diuretic amiloride. They mediate the electrodiffusion of the luminal sodium (and water, which follows osmotically) through the apical membrane of epithelial cells. In vertebrates, these channels control the reabsorption of sodium in kidney, colon, lung and sweat glands. They also play a role in taste perception. The ASC are composed of three homologous subunits, called α, β and γ. A fourth subunit (delta) can replace the α subunit [4]. The vertebrate ASC subunits are homologous to the degenerins [5] of Caenorhabditis elegans: deg-1, del-1, mec-4, mec-10 and unc-8. They are proteins that can be mutated to cause neuronal degradation. They are also thought to form sodium channels.

This family also includes:

  • Mammalian amiloride-sensitive brain sodium channel BNAC1 (also known as degenerin channel MDEG). This is a cation channel permeable for sodium, potassium and lithium.
  • Caenorhabditis elegans hypothetical proteins C41C4.5, T28F4.2 and ZK770.1.

Structurally, the proteins that belong to this family consist of about 510 to 920 amino acid residues. They are made of an intracellular N-terminus region followed by a transmembrane domain, a large extracellular loop, a second transmembrane segment and a C-terminal intracellular tail [6].

The signature we developed to pick up these proteins corresponds to the beginning of a conserved cysteine-rich region (there are nine conserved cysteines in a domain of about 65 residues) located at the C-terminal part of the extracellular loop.

Last update:

April 2006 / Pattern revised.


Technical section

PROSITE method (with tools and information) covered by this documentation:

ASC, PS01206; Amiloride-sensitive sodium channels signature  (PATTERN)


1AuthorsGarty H.
TitleMolecular properties of epithelial, amiloride-blockable Na+ channels.
SourceFASEB J. 8:522-528(1994).
PubMed ID8181670

2AuthorsJentsch T.J.
TitleTrinity of cation channels.
SourceNature 367:412-413(1994).
PubMed ID7509038

3AuthorsLe T. Saier M.H. Jr.
TitlePhylogenetic characterization of the epithelial Na+ channel (ENaC) family.
SourceMol. Membr. Biol. 13:149-157(1996).
PubMed ID8905643

4AuthorsGarcia-Anoveros J. Ma C. Chalfie M.
SourceCurr. Biol. 5:441-448(1995).

5AuthorsWaldmann R. Champigny G. Bassilana F. Voilley N. Lazdunski M.
TitleMolecular cloning and functional expression of a novel amiloride-sensitive Na+ channel.
SourceJ. Biol. Chem. 270:27411-27414(1995).
PubMed ID7499195

6AuthorsSnyder P.M. McDonald F.J. Stokes J.B. Welsh M.J.
TitleMembrane topology of the amiloride-sensitive epithelial sodium channel.
SourceJ. Biol. Chem. 269:24379-24383(1994).
PubMed ID7929098

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