PROSITE documentation PDOC00328

Sodium and potassium ATPases beta subunits signatures




Description

The sodium pump (Na+,K+ ATPase), located in the plasma membrane of all animal cells [1], is an heterotrimer of a catalytic subunit (α chain), a glycoprotein subunit of about 34 Kd (β chain) and a small hydrophobic protein of about 6 Kd. The β subunit seems [2] to regulate, through the assembly of α/β heterodimers, the number of sodium pumps transported to the plasma membrane.

Structurally the β subunit is composed of a charged cytoplasmic domain of about 35 residues, followed by a transmembrane region, and a large extracellular domain that contains three disulfide bonds and glycosylation sites. This structure is schematically represented in the figure below.

                                +----+ +--+       +-----------+
                                |    | |  |       |           |
        xxxxxxxxxxxxxxxxxxxxxxxxCxxxxCxCxxCxxxxxxxCxxxxxxxxxxxCxxxx
           ****                      ****
        <-Cyt-><TM><------------Extracellular--------------------->
'C': conserved cysteine involved in a disulfide bond.
'*': position of the patterns.

Four isoforms of the β subunit (β-1 to β-4) are currently known.

Gastric (K+, H+) ATPase (proton pump) responsible for acid production in the stomach consist of two subunits [3]; the β chain is highly similar to the sodium pump β subunits.

We developed two signature patterns for β subunits. The first is located in the cytoplasmic domain, while the second is found in the extracellular domain and contains two of the cysteines involved in disulfide bonds.

Last update:

December 2004 / Pattern and text revised.

Technical section

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

ATPASE_NA_K_BETA_1, PS00390; Sodium and potassium ATPases beta subunits signature 1  (PATTERN)

ATPASE_NA_K_BETA_2, PS00391; Sodium and potassium ATPases beta subunits signature 2  (PATTERN)


References

1AuthorsHorisberger J.D., Lemas V., Kraehenbuhl J.P., Rossier B.C.
TitleStructure-function relationship of Na,K-ATPase.
SourceAnnu. Rev. Physiol. 53:565-584(1991).
PubMed ID1645948
DOI10.1146/annurev.ph.53.030191.003025

2AuthorsMcDonough A.A., Geering K., Farley R.A.
TitleThe sodium pump needs its beta subunit.
SourceFASEB J. 4:1598-1605(1990).
PubMed ID2156741

3AuthorsToh B.-H., Gleeson P.A., Simpson R.J., Moritz R.L., Callaghan J.M., Goldkorn I., Jones C.M., Martinelli T.M., Mu F.-T., Humphris D.C.
TitleThe 60- to 90-kDa parietal cell autoantigen associated with autoimmune gastritis is a beta subunit of the gastric H+/K(+)-ATPase (proton pump).
SourceProc. Natl. Acad. Sci. U.S.A. 87:6418-6422(1990).
PubMed ID1974721



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