a ganglioside GM2 (d18:1(4E)) + UDP + H(+) => a ganglioside GM3 (d18:1(4E)) + UDP-N-acetyl-alpha-D-galactosamine
a ganglioside gm2 (d18:1(4e)) + udp + h(+) => a ganglioside gm3 (d18:1(4e)) + udp-n-acetyl-alpha-d-galactosamine