The protein encoded by this gene binds to cell surfaces through a glycosylphosphatidylinositol (GPI) linkage. The encoded glycoprotein is found on activated lymphocytes and erythrocytes. This protein may be involved in immunomodulatory and neuronal processes. Defects in this gene can result in loss of bone mineral density (BMD). Three transcript variants encoding different isoforms have been found for this gene.