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

		+			=			+
	UDPgalactose	+		p-nitrophenyl beta-D-xylose	=		UDP	+		beta-D-galactosyl-1,4-beta-D-xylosyl-1-O-nitrophenol