Cytosolic aldo-keto reductase that catalyzes the NADH and NADPH-dependent reduction of ketosteroids to hydroxysteroids (PubMed:15618685). Most probably acts as a reductase in vivo since the oxidase activity measured in vitro is inhibited by physiological concentrations of NADPH (By similarity). Displays a broad positional specificity acting on positions 3, 17 and 20 of steroids and regulates the metabolism of hormones like estrogens and androgens (PubMed:15618685). May also reduce conjugated steroids such as 5alpha-dihydrotestosterone sulfate. Displays affinity for bile acids (By similarity). Can also act on non-steroidal substrates such as S-indan-1-ol, S-tetralol and 4-chromanol (PubMed:15618685). a 3alpha-hydroxysteroid + NADP(+) = a 3-oxosteroid + H(+) + NADPH a 3alpha-hydroxysteroid + NAD(+) = a 3-oxosteroid + H(+) + NADH (17R,20S)-17,20-dihydroxypregn-4-en-3-one + NADP(+) = 17alpha-hydroxyprogesterone + H(+) + NADPH (17R,20S)-17,20-dihydroxypregn-4-en-3-one + NAD(+) = 17alpha-hydroxyprogesterone + H(+) + NADH (20S)-hydroxypregn-4-en-3-one + NADP(+) = H(+) + NADPH + progesterone (20S)-hydroxypregn-4-en-3-one + NAD(+) = H(+) + NADH + progesterone (1R,2R)-1,2-dihydrobenzene-1,2-diol + NADP(+) = catechol + H(+) + NADPH (S)-indan-1-ol + NAD(+) = H(+) + indan-1-one + NADH (S)-indan-1-ol + NADP(+) = H(+) + indan-1-one + NADPH 5alpha-androstane-3alpha,17beta-diol + NADP(+) = 17beta-hydroxy-5alpha-androstan-3-one + H(+) + NADPH 5alpha-androstane-3beta,17beta-diol + NADP(+) = 17beta-hydroxy-5alpha-androstan-3-one + H(+) + NADPH 5alpha-androstane-3alpha,17beta-diol + NAD(+) = 17beta-hydroxy-5alpha-androstan-3-one + H(+) + NADH 17beta-hydroxy-5alpha-androstan-3-one + NADP(+) = 5alpha-androstan-3,17-dione + H(+) + NADPH 3alpha-hydroxy-5alpha-androstan-17-one + NADP(+) = 5alpha-androstan-3,17-dione + H(+) + NADPH 3alpha-hydroxy-5alpha-androstan-17-one + H(+) + NADPH = 5alpha-androstane-3alpha,17beta-diol + NADP(+) 5alpha-androstane-3alpha,17beta-diol + NAD(+) = 3alpha-hydroxy-5alpha-androstan-17-one + H(+) + NADH 17beta-estradiol + NADP(+) = estrone + H(+) + NADPH 17beta-estradiol + NAD(+) = estrone + H(+) + NADH NADP(+) + testosterone = androst-4-ene-3,17-dione + H(+) + NADPH 20alpha-hydroxy-5beta-pregnan-3-one + NADP(+) = 5beta-pregnan-3,20-dione + H(+) + NADPH 3beta-hydroxy-5beta-pregnane-20-one + NADP(+) = 5beta-pregnan-3,20-dione + H(+) + NADPH 3beta-hydroxy-5beta-pregnane-20-one + H(+) + NADPH = 3beta,20alpha-dihydroxy-5beta-pregnane + NADP(+) (3beta,5alpha,17beta)-3-hydroxyandrostan-17-yl sulfate + NADP(+) = 5alpha-dihydrotestosterone sulfate + H(+) + NADPH Potently inhibited by benzbromarone and 3',3'',5',5''-tetrabromophenolphthalein (TBPP). Steroid metabolism. Monomer. Belongs to the aldo/keto reductase family.