BCAP31 is a member of the B-cell receptor associated protein 31 superfamily. It is a multi-pass transmembrane protein of the endoplasmic reticulum that is involved in the anterograde transport of membrane proteins from the endoplasmic reticulum to the Golgi and in the caspase 8-mediated apoptosis. Microdeletions in this gene are associated with the contiguous ABCD1/DXS1375E deletion syndrome.