Involved in the biosynthesis of gangliosides GM2, GD2 and GA2. 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 GD3 (d18:1(4E)) + UDP-N-acetyl-alpha-D-galactosamine = ganglioside GD2 (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 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 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 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. Most abundant in brain, liver, lung, spleen and testis. Highest at day 7 of embryonic development after which it declines to its lowest levels at day 11 before increasing again. No visible phenotype, excepting a slight decrease in neural conduction velocity from the tibial nerve to the somatosensory cortex (PubMed:8855236). Mutant mice display impaired motor coordination and balance (PubMed:15953602). Sciatic nerves from over three month old mutant mice show signs of Wallerian degeneration, with redundant myelin, degeneration of myelinated fibers, axon dysmyelination, and an apparent decrease in the diameter of myelinated axons (PubMed:15953602). The distances between neurofilaments in myelinated axons from over 3 month old mice are shorter than normal (PubMed:15953602). Mice are less sensitive to C.botulinum neurotoxin type C (BoNT/C), C.botulinum neurotoxin type D (BoNT/D, botD) and C.botulinum neurotoxin type F (BoNT/F, botF) (PubMed:21483489). Belongs to the glycosyltransferase 2 family. Beta-1,4 N-acetylgalactosaminyltransferase 1