B3GALT6 (Beta-1,3-galactosyltransferase) transfers galactose from UDP-galactose to substrates with a terminal beta-linked galactose residue. It has a preference for galactose-beta-1,4-xylose that is found in the linker region of glycosaminoglycans, such as heparan sulfate and chondroitin sulfate. It has no activity towards substrates with terminal glucosamine or galactosamine residues.