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

		+			=			+
	UDPgalactose	+		4-methylumbelliferyl-beta-D-xyloside	=		UDP	+		beta-D-galactosyl-1,4-beta-D-xylosyl-1-O-(4-methylumbelliferone)