Reaction catalyzed by glycogen phosphorylase (2.4.1.1)

		+			=			+
	maltotetraose	+		2-amino-2-deoxy-alpha-D-glucopyranosyl 1-phosphate	=		GlcNAc-alpha-(1->4)-Glc-alpha-(1->4)-Glc-alpha-(1->4)-Glc-alpha-(1->4)-Glcalpha	+		phosphate