Cytosolic aldo-keto reductase that catalyzes the NADH and NADPH-dependent reduction of ketosteroids to hydroxysteroids. Acts as a NAD(P)(H)-dependent 3-, 17- and 20-ketosteroid reductase on the steroid nucleus and side chain and regulates the metabolism of androgens, estrogens and progesterone (PubMed:10622721, PubMed:11165022, PubMed:7650035, PubMed:9415401, PubMed:9927279). Displays the ability to catalyze both oxidation and reduction in vitro, but most probably acts as a reductase in vivo since the oxidase activity measured in vitro is inhibited by physiological concentration of NADPH (PubMed:14672942, PubMed:11165022). Acts preferentially as a 17-ketosteroid reductase and has the highest catalytic efficiency of the AKR1C enzyme for the reduction of delta4-androstenedione to form testosterone (PubMed:20036328). Reduces prostaglandin (PG) D2 to 11beta-prostaglandin F2, progesterone to 20alpha-hydroxyprogesterone and estrone to 17beta-estradiol (PubMed:15047184, PubMed:20036328, PubMed:10622721, PubMed:11165022, PubMed:10998348, PubMed:19010934). Catalyzes the transformation of the potent androgen dihydrotestosterone (DHT) into the less active form, 5-alpha-androstan-3-alpha,17-beta-diol (3-alpha-diol) (PubMed:10998348, PubMed:14672942, PubMed:11165022, PubMed:7650035, PubMed:9415401, PubMed:10557352). Also displays retinaldehyde reductase activity toward 9-cis-retinal (PubMed:21851338). a 3alpha-hydroxysteroid + NADP(+) = a 3-oxosteroid + H(+) + NADPH a 3alpha-hydroxysteroid + NAD(+) = a 3-oxosteroid + H(+) + NADH NADP(+) + prostaglandin F2alpha = H(+) + NADPH + prostaglandin D2 NADP(+) + prostaglandin F2alpha = H(+) + NADPH + prostaglandin H2 H(+) + NADPH + prostaglandin D2 = 11beta-prostaglandin F2 + NADP(+) H(+) + NADPH + prostaglandin D2-ethanolamide = 11beta-prostaglandin F2-ethanolamide + NADP(+) NAD(+) + testosterone = androst-4-ene-3,17-dione + H(+) + NADH NADP(+) + testosterone = androst-4-ene-3,17-dione + H(+) + NADPH 17beta-estradiol + NADP(+) = estrone + H(+) + NADPH 17beta-estradiol + NAD(+) = estrone + H(+) + NADH (20S)-hydroxypregn-4-en-3-one + NADP(+) = H(+) + NADPH + progesterone (20S)-hydroxypregn-4-en-3-one + NAD(+) = H(+) + NADH + progesterone 5alpha-androstane-3alpha,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 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 5alpha-androstane-3beta,17beta-diol + NADP(+) = 17beta-hydroxy-5alpha-androstan-3-one + H(+) + NADPH 9-cis-retinol + NADP(+) = 9-cis-retinal + H(+) + NADPH Strongly inhibited by nonsteroidal anti-inflammatory drugs (NSAID) including flufenamic acid and indomethacin. Also inhibited by the flavinoid, rutin, and by selective serotonin inhibitors (SSRIs) (PubMed:14979715, PubMed:14996743, PubMed:10557352). The oxidation reaction is inhibited by low micromolar concentrations of NADPH (PubMed:14672942). kcat is 0.044 min(-1) for testosterone oxydation (PubMed:10998348). kcat is 13 min(-1) for 9-cis-retinal as substrate (PubMed:21851338). kcat is 4.18 min(-1) for 17beta-hydroxy-5alpha-androstan-3-one reduction (PubMed:10998348). kcat is 0.37 min(-1) for 3alpha-hydroxy-5alpha-androstan-17-one reduction (PubMed:10998348). kcat is 0.046 min(-1) for 17beta-hydroxy-5alpha-androstan-3-one oxydation (PubMed:10998348). Steroid metabolism. Expressed in many tissues including adrenal gland, brain, kidney, liver, lung, mammary gland, placenta, small intestine, colon, spleen, prostate and testis. High expression in prostate and mammary gland. In the prostate, higher levels in epithelial cells than in stromal cells. In the brain, expressed in medulla, spinal cord, frontotemporal lobes, thalamus, subthalamic nuclei and amygdala. Weaker expression in the hippocampus, substantia nigra and caudate. Belongs to the aldo/keto reductase family. Truncated N-terminus.