Reaction catalyzed by beta-1,4-mannosyl-glycoprotein 4-beta-N-acetylglucosaminyltransferase (2.4.1.144)

		+			=			+
	UDP-N-acetyl-D-glucosamine	+		beta-D-mannosyl-R	=		UDP	+		4-(N-acetyl-beta-D-glucosaminyl)-beta-D-mannosyl-R