Reaction catalyzed by protein xylosyltransferase (2.4.2.26)

		+			=			+
	UDP-D-xylose	+		biotin-NH-QEEEGSGGGQKK(5-fluorescein)-CONH2	=		UDP	+		biotin-NH-QEEEGS(D-xylosyl)GGGQKK(5-fluorescein)-CONH2