This gene encodes a member of the FXYD family of transmembrane proteins. This particular protein encodes phosphohippolin, which likely affects the activity of Na,K-ATPase. Multiple alternatively spliced transcript variants encoding the same protein have been described. Related pseudogenes have been identified on chromosomes 10 and X. Read-through transcripts have been observed between this locus and the downstream sodium/potassium-transporting ATPase subunit gamma (FXYD2, GeneID 486) locus.