Anti-uroplakin 3B antibodies are used in the immunodetection of the protein encoded by the UPK3B gene. In humans, the canonical protein has a reported length of 320 amino acid residues and a mass of 33.9 kDa. Its subcellular localization is in the cell membrane. Alternative splicing is reported to yield 3 different isoforms for this protein. A member of the Uroplakin-3 protein family, it is a known component of the asymmetric unit membrane (AUM); a highly specialized biomembrane elaborated by terminally differentiated urothelial cells. Post-translational modifications have been described, including glycosylation. Other names for this target antigen include uroplakin IIIb.