an N-acetyl-beta-D-galactosaminyl-(1->4)-N-acetyl-beta-D-glucosaminyl derivative + UDP + H(+) => an N-acetyl-beta-D-glucosaminyl derivative + UDP-N-acetyl-alpha-D-galactosamine
an n-acetyl-beta-d-galactosaminyl-(1->4)-n-acetyl-beta-d-glucosaminyl derivative + udp + h(+) => an n-acetyl-beta-d-glucosaminyl derivative + udp-n-acetyl-alpha-d-galactosamine