This gene encodes a protein product localized to the lumen of the endoplasmic reticulum. As a member of the endoplasmic reticulum protein family the encoded protein contains a Lys-Asp-Glu-Leu or KDEL motif located at the extreme C-terminus which prevents all endoplasmic reticulum resident proteins from being secreted. Proteins carrying this motif are bound by a receptor in the Golgi apparatus so that the receptor-ligand complex returns to the endoplasmic reticulum. A processed non-transcribed pseudogene located in an intron of a sodium transporter gene on chromosome 5 has been defined for this gene. This gene has multiple transcript variants which are predicted to encode distinct isoforms. [provided by RefSeq, Jan 2016].