Anti-B2M antibodies are used in the immunodetection of the protein beta-2-microglobulin. In humans, the canonical protein has a reported length of 119 amino acid residues and a mass of 13.7 kDa. It has been described to be a secreted protein. It is notably widely expressed in many tissue types. A member of the Beta-2-microglobulin protein family, B2M is a known component of the class I major histocompatibility complex (MHC). Post-translational modifications have been described, including glycosylation. The B2M gene has been associated with the disease, Immunodeficiency. Synonyms for this target antigen include beta chain of MHC class I molecules, beta-2-microglobin, and IMD43. B2M gene orthologs have been reported in the mouse, rat, frog, chimpanzee and chicken species.