NAD-dependent oxidoreductase with broad substrate specificity that shows both oxidative and reductive activity (in vitro). Has 17-beta-hydroxysteroid dehydrogenase activity towards various steroids (in vitro). Converts 5-alpha-androstan-3-alpha,17-beta-diol to androsterone and estradiol to estrone (in vitro). Has 3-alpha-hydroxysteroid dehydrogenase activity towards androsterone (in vitro). Has retinol dehydrogenase activity towards all-trans-retinol (in vitro). Can convert androsterone to epi-androsterone. Androsterone is first oxidized to 5-alpha-androstane-3,17-dione and then reduced to epi-andosterone. Can act on both C-19 and C-21 3-alpha-hydroxysteroids.

Tissue specificity; Detected in liver and prostate (at protein level). Detected in adult liver, lung, brain, placenta, prostate, adrenal gland, testis, mammary gland, spleen, spinal cord and uterus. Detected in caudate nucleus, and at lower levels in amygdala, corpus callosum, hippocampus, substantia nigra and thalamus. Detected in fetal lung, liver and brain.

Sequence similarities; Belongs to the short-chain dehydrogenases/reductases (SDR) family.