Reaction catalyzed by 3alpha(or 20beta)-hydroxysteroid dehydrogenase (1.1.1.53)

		+		NADH	=			+		NAD+
	3,20-dioxo-4-pregnen-21-oic acid	+		NADH	=		20beta-hydroxy-3-oxo-4-pregnen-21-oic acid	+		NAD+