. "5Beta-cholesten-7alpha,12alpha-diol-3-one and NADPH + H+ form 5beta-cholestan-3alpha,7alpha,12alpha-triol and NAPDP+. The reaction is catalyzed by 3alpha-hydroxysteroid dehydrogenase (AKR1C4), a cytosolic enzyme belonging to the aldo-keto reductase family (Dufort et al. 2001). Biochemical studies with rat proteins raise the possibility that other related enzymes may also carry out this reaction in vivo (Russell 2003)."^^ . . . .