N,N'-diacetyl-alpha-D-bacillosaminyl-tri-trans,hepta-cis-undecaprenyl diphosphate + UDP-N-acetyl-alpha-D-galactosamine = N-acetyl-alpha-D-galactosaminyl-(1->3)-N,N'-diacetyl-alpha-D-bacillosaminyl-tri-trans,hepta-cis-undecaprenyl diphosphate + UDP + H(+)
n,n'-diacetyl-alpha-d-bacillosaminyl-tri-trans,hepta-cis-undecaprenyl diphosphate + udp-n-acetyl-alpha-d-galactosamine = n-acetyl-alpha-d-galactosaminyl-(1->3)-n,n'-diacetyl-alpha-d-bacillosaminyl-tri-trans,hepta-cis-undecaprenyl diphosphate + udp + h(+)