a ganglioside GM2 (d18:1(4E)) + CMP + H(+) => a ganglioside GA2 (d18:1(4E)) + CMP-N-acetyl-beta-neuraminate
a ganglioside gm2 (d18:1(4e)) + cmp + h(+) => a ganglioside ga2 (d18:1(4e)) + cmp-n-acetyl-beta-neuraminate