Anti-UDP glucuronosyltransferase family 1 member A1 antibodies are used in the immunodetection of the protein encoded by the UGT1A1 gene. In humans, the canonical protein has a reported length of 533 amino acid residues and a mass of 59.6 kDa. Its subcellular localization is in the ER and cytoplasm. Alternative splicing is reported to yield 2 different isoforms for this protein. A member of the UDP-glycosyltransferase protein family, it is reported to be a UDP-glucuronosyltransferase (UGT) that catalyzes phase II biotransformation reactions in which lipophilic substrates are conjugated with glucuronic acid to increase the metabolite's water solubility, thereby facilitating excretion into either the urine or bile. Post-translational modifications have been described, including glycosylation. Other names for this target antigen include BILIQTL1 and GNT1.