Involved in the biosynthesis of gangliosides GM2, GD2, GT2 and GA2 from GM3, GD3, GT3 and GA3, respectively. ganglioside GM3 (d18:1(4E)) + UDP-N-acetyl-alpha-D-galactosamine = ganglioside GM2 (d18:1(4E)) + H(+) + UDP ganglioside GM3 + UDP-N-acetyl-alpha-D-galactosamine = ganglioside GM2 + H(+) + UDP ganglioside GD3 + UDP-N-acetyl-alpha-D-galactosamine = ganglioside GD2 + H(+) + UDP ganglioside GD3 (d18:1(4E)) + UDP-N-acetyl-alpha-D-galactosamine = ganglioside GD2 (d18:1(4E)) + H(+) + UDP a beta-D-Gal-(1->4)-beta-D-Glc-(1<->1)-Cer(d18:1(4E)) + UDP-N-acetyl-alpha-D-galactosamine = ganglioside GA2 (d18:1(4E)) + H(+) + UDP ganglioside GD1a + UDP-N-acetyl-alpha-D-galactosamine = ganglioside GalNAc-GD1a + H(+) + UDP ganglioside GT3 (d18:1(4E)) + UDP-N-acetyl-alpha-D-galactosamine = ganglioside GT2 (d18:1(4E)) + H(+) + UDP beta-D-galactosyl-(1->4)-beta-D-glucosyl-(1<->1)-ceramide + UDP-N-acetyl-alpha-D-galactosamine = H(+) + N-acetyl-beta-D-galactosaminyl-(1->4)-beta-D-galactosyl-(1->4)-beta-D-glucosyl-(1<->1')-ceramide + UDP alpha-N-glycoloylneuraminosyl-(2->3)-beta-D-galactosyl-(1->4)-N-acetyl-beta-D-glucosaminyl-(1->3)-beta-D-galactosyl-(1->4)-beta-D-glucosyl-(1<->1')-ceramide + UDP-N-acetyl-alpha-D-galactosamine = H(+) + N-acetyl-beta-D-galactosaminyl-(1->4)-[alpha-N-glycoloylneuraminosyl-(2->3)]-beta-D-galactosyl-(1->4)-N-acetyl-beta-D-glucosaminyl-(1->3)-beta-D-galactosyl-(1->4)-beta-D-glucosyl-(1<->1')-ceramide + UDP Sphingolipid metabolism. Homodimer; disulfide-linked. The disease is caused by variants affecting the gene represented in this entry. Belongs to the glycosyltransferase 2 family. Beta-1,4 N-acetylgalactosaminyltransferase 1