preferred_name: an N-acetyl-beta-D-galactosaminyl-(1->4)-[N-acetyl-alpha-neuraminyl-(2->3)]-beta-D-galactosyl derivative + UDP + H(+) => an N-acetyl-alpha-neuraminyl-(2->3)-beta-D-galactosyl derivative + UDP-N-acetyl-alpha-D-galactosamine