Involved in the biosynthesis of gangliosides GM2, GD2, GT2 and GA2 from GM3, GD3, GT3 and GA3, respectively. {ECO:0000269|PubMed:1601877, ECO:0000269|PubMed:7487055, ECO:0000269|PubMed:7890749}. This is the function of B4GALNT1 (beta-1,4-N-acetyl-galactosaminyltransferase 1, ENSG00000135454).