Reaction catalyzed by mannosylglycoprotein endo-beta-mannosidase (3.2.1.152)

		+			=			+		GlcNAc-peptide
	Man-beta-(1-4)GlcNAc-beta-(1-4)GlcNAc-peptide	+		p-nitrophenyl-beta-D-glucoside	=		Man-beta-(1-4)GlcNAc-beta-(1-4)Glc-beta-1-p-nitrophenyl	+		GlcNAc-peptide