FXYD3 (Mat-8), a new regulator of Na,K-ATPase

Mol Biol Cell. 2005 May;16(5):2363-71. doi: 10.1091/mbc.e04-10-0878. Epub 2005 Mar 2.


Four of the seven members of the FXYD protein family have been identified as specific regulators of Na,K-ATPase. In this study, we show that FXYD3, also known as Mat-8, is able to associate with and to modify the transport properties of Na,K-ATPase. In addition to this shared function, FXYD3 displays some uncommon characteristics. First, in contrast to other FXYD proteins, which were shown to be type I membrane proteins, FXYD3 may have a second transmembrane-like domain because of the presence of a noncleavable signal peptide. Second, FXYD3 can associate with Na,K- as well as H,K-ATPases when expressed in Xenopus oocytes. However, in situ (stomach), FXYD3 is associated only with Na,K-ATPase because its expression is restricted to mucous cells in which H,K-ATPase is absent. Coexpressed in Xenopus oocytes, FXYD3 modulates the glycosylation processing of the beta subunit of X,K-ATPase dependent on the presence of the signal peptide. Finally, FXYD3 decreases both the apparent affinity for Na+ and K+ of Na,K-ATPase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Cloning, Molecular
  • Female
  • Gastric Mucosa / metabolism
  • Glycosylation
  • H(+)-K(+)-Exchanging ATPase / chemistry
  • H(+)-K(+)-Exchanging ATPase / metabolism
  • In Vitro Techniques
  • Membrane Proteins / chemistry
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Mice
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Neoplasm Proteins / chemistry
  • Neoplasm Proteins / genetics
  • Neoplasm Proteins / metabolism*
  • Oocytes / metabolism
  • Protein Processing, Post-Translational
  • Protein Sorting Signals / genetics
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Sequence Homology, Amino Acid
  • Sodium-Potassium-Exchanging ATPase / chemistry
  • Sodium-Potassium-Exchanging ATPase / metabolism*
  • Xenopus laevis


  • Fxyd3 protein, mouse
  • Membrane Proteins
  • Neoplasm Proteins
  • Protein Sorting Signals
  • Recombinant Proteins
  • H(+)-K(+)-Exchanging ATPase
  • Sodium-Potassium-Exchanging ATPase