Reaction catalyzed by globotriaosylceramide 3-beta-N-acetylgalactosaminyltransferase (2.4.1.79)

		+			=			+
	UDP-N-acetyl-D-galactosamine	+		D-galactosyl-1,4-D-galactosyl-1,4-D-glucosylceramide	=		UDP	+		N-acetyl-D-galactosaminyl-1,3-D-galactosyl-1,4-D-galactosyl-1,4-D-glucosylceramide