FXYD Domain Containing Ion Transport Regulator 4 (FXYD4)

FXYD4 encodes a member of a family of small membrane proteins that share a 35-amino acid signature sequence domain, beginning with the sequence PFXYD and containing 7 invariant and 6 highly conserved amino acids. The approved human gene nomenclature for the family is FXYD-domain containing ion transport regulator. FXYD4, originally named CHIF for channel-inducing factor, has been shown to modulate the properties of the Na,K-ATPase, as has FXYD2, also known as the gamma subunit of the Na,K-ATPase, and FXYD7. Transmembrane topology has been established for FXYD4 and two family members (FXYD1 and FXYD2), with the N-terminus extracellular and the C-terminus on the cytoplasmic side of the membrane. Alternatively spliced transcript variants encoding the same protein have been found.[