β-1,3-Gal-T5 Background Information ∫-1,3-Gal-T5 belongs to the glycosyltransferase 31 family and catalyzes the transfer of Gal to GlcNAc-based acceptors with a preference for the core3 O-linked glycan GlcNAc(beta1,3)GalNAc structure. ∫-1,3-Gal-T5 is a type II membrane protein, and exhibits expression in stomach, jejunum, colon, pancreas, small intestine, testis and gastrointestinal and pancreatic cancer cell lines. Small levels are detected in lung, liver, adrenal gland and peripheral blood leukocytes. ∫-1,3-Gal-T5 also determines the amounts of the type 1 Lewis antigens including the sialyl Lewis a antigen and is likely responsible for the synthesis of the type 1 Lewis antigens in gastrointestinal and pancreatic epithelia and tumor cells.