?-1,3-Gal-T6 (beta-1,3-galactosyltransferase 6), also known as galactosyltransferase II or GAG GalTII, is a 329 amino acid protein belonging to the glycosyltransferase 31 family. ?-1,3-Gal-T6 is involved in several glycan metabolism pathways. With manganese as a cofactor, ?-1,3-Gal-T6 catalyzes the transfer of galactose from UDP-galactose to substrates with a terminal beta-linked galactose residue. ?-1,3-Gal-T6 has a preference for galactose-beta-1,4-xylose found in the linker region of chondroitin sulfate, heparan sulfate and other glycosaminoglycans, but does not have activity towards substrates with terminal galactosamine or glucosamine residues. Ubiquitously expressed, ?-1,3-Gal-T6 is a single-pass type II membrane protein localized to the Golgi stack membrane.