Anti-biglycan antibodies are used in the immunodetection of the protein encoded by the BGN gene. In humans, the canonical protein has a reported length of 368 amino acid residues and a mass of 41.7 kDa. Its subcellular localization is in the extracellular matrix and is also secreted. It is notably expressed in placenta. A member of the Small leucine-rich proteoglycan (SLRP) protein family, it is suspected to be involved in collagen fiber assembly. Post-translational modifications have been described, including glycosylation. Other names for this target antigen include MRLS, PG-S1, PGI, SEMDX, SLRR1A, bone/cartilage proteoglycan-I, dermatan sulphate proteoglycan I, and DSPG1.