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  • The EMBO Journal (2002) 21, 3264 - 3273
  • doi:10.1093/emboj/cdf330

FXYD7 is a brain-specific regulator of Na,K-ATPase alpha1–bold beta isozymes

Pascal Béguin1,4, Gilles Crambert1,4, Florianne Monnet-Tschudi2, Marc Uldry1, Jean-Daniel Horisberger1, Haim Garty3 and Käthi Geering1

  1. Institute of Pharmacology and Toxicology, University of Lausanne, rue du Bugnon 27, CH-1005 Lausanne, Switzerland
  2. Institute of Physiology, University of Lausanne, rue du Bugnon 27, CH-1005 Lausanne, Switzerland
  3. Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100 Israel
  4. P.Béguin and G.Crambert contributed equally to this work

Correspondence to:

Käthi Geering, E-mail: kaethi.geering@ipharm.unil.ch

Received 6 March 2002; Accepted 6 May 2002; Revised 26 April 2002

Recently, corticosteroid hormone-induced factor (CHIF) and the gamma-subunit, two members of the FXYD family of small proteins, have been identified as regulators of renal Na,K-ATPase. In this study, we have investigated the tissue distribution and the structural and functional properties of FXYD7, another family member which has not yet been characterized. Expressed exclusively in the brain, FXYD7 is a type I membrane protein bearing N-terminal, post-translationally added modifications on threonine residues, most probably O-glycosylations that are important for protein stabilization. Expressed in Xenopus oocytes, FXYD7 can interact with Na,K-ATPase alpha1–beta1, alpha2–beta1 and alpha3–beta1 but not with alpha–beta2 isozymes, whereas, in brain, it is only associated with alpha1–beta isozymes. FXYD7 decreases the apparent K+ affinity of alpha1–beta1 and alpha2–beta1, but not of alpha3–beta1 isozymes. These data suggest that FXYD7 is a novel, tissue- and isoform-specific Na,K-ATPase regulator which could play an important role in neuronal excitability.

  • Keywords:

    • brain Na,K-ATPase modulator,
    • FXYD7,
    • FXYD proteins,
    • Xenopus oocytes