ST3GAL family transfers sialic acid from CMP-Sia to the terminal galactose residues of glycochains through an 2,3-linkage. ST3GAL4 can utilize both Galbeta1,3GlcNAc and Galbeta1,4GlcNAc, mainly on glycoproteins and oligosaccharidesas acceptor substrates, but prefers the Galbeta1,4GlcNAc. Members of this family belong to glycosyltransferase family 29 (GT29).