FXYD3 (Mat-8), a new regulator of Na,K-ATPase.
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.
Mesh Terms:
Amino Acid Sequence, Animals, Cloning, Molecular, Female, Gastric Mucosa, Glycosylation, H(+)-K(+)-Exchanging ATPase, Membrane Proteins, Mice, Molecular Sequence Data, Mutagenesis, Site-Directed, Neoplasm Proteins, Oocytes, Protein Processing, Post-Translational, Protein Sorting Signals, Recombinant Proteins, Sequence Homology, Amino Acid, Sodium-Potassium-Exchanging ATPase, Xenopus laevis
Amino Acid Sequence, Animals, Cloning, Molecular, Female, Gastric Mucosa, Glycosylation, H(+)-K(+)-Exchanging ATPase, Membrane Proteins, Mice, Molecular Sequence Data, Mutagenesis, Site-Directed, Neoplasm Proteins, Oocytes, Protein Processing, Post-Translational, Protein Sorting Signals, Recombinant Proteins, Sequence Homology, Amino Acid, Sodium-Potassium-Exchanging ATPase, Xenopus laevis
Mol. Biol. Cell
Date: May. 01, 2005
PubMed ID: 15743908
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