Reaction catalyzed by methylenetetrahydrofolate reductase [NAD(P)H] (1.5.1.20)

		+			=			+
	5-methyltetrahydropteroylmonoglutamate	+		5,10-methylenetetrahydropteroylhexaglutamate	=		5,10-methylenetetrahydropteroylmonoglutamate	+		5-methyltetrahydropteroylhexaglutamate