preferred_name: 3-O-(N-acetyl-beta-D-glucosaminyl-(1->4)-alpha-D-mannosyl)-L-threonyl-[protein] + UDP-N-acetyl-alpha-D-galactosamine <=> 3-O-[beta-D-GalNAc-(1->3)-beta-D-GlcNAc-(1->4)-alpha-D-Man]-L-Thr-[protein] + UDP + H(+)