Cytosolic aldo-keto reductase that catalyzes the NADH and NADPH-dependent reduction of ketosteroids to hydroxysteroids . 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 . 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 .
Subcellular locations: Cytoplasm, Cytosol