Reaction catalyzed by xylosylprotein 4-beta-galactosyltransferase (2.4.1.133)

		+			=			+
	UDPgalactose	+		p-nitrophenyl N-acetyl-beta-D-glucosaminide	=		UDP	+		beta-D-galactosyl-1,4-N-acetyl-beta-D-glucosaminide-1-O-nitrophenol