Reaction catalyzed by glucuronosyl-N-acetylglucosaminyl-proteoglycan 4-alpha-N-acetylglucosaminyltransferase (2.4.1.224)

		+			=			+
	UDP-N-acetyl-D-glucosamine	+		beta-D-glucuronosyl-(1->4)-N-acetyl-alpha-D-glucosaminyl-proteoglycan	=		UDP	+		N-acetyl-alpha-D-glucosaminyl-(1->4)-beta-D-glucuronosyl-(1->4)-N-acetyl-alpha-D-glucosaminyl-proteoglycan