NADPH-dependent oxidoreductase which catalyzes the reduction of a variety of compounds bearing carbonyl groups including steroids, retinoids and xenobiotics. Catalyzes the reduction/inactivation of 5alpha-dihydrotestosterone to 3alpha-androstanediol, with a possible role in the modulation of androgen receptor function. Involved in the reduction of all-trans-retinal to all-trans-retinol. Converts cortisone to 20beta-dihydrocortisone in vitro, although the physiological relevance of this activity is questionable. Reduces exogenous compounds such as quinones (1,2-naphtoquinone, 9,10-phenantrenequinone and benzoquinone) and other xenobiotics (alpha-diketones) in vitro, suggesting a role in the biotransformation of xenobiotics with carbonyl group. A dehydrogenase activity has not been detected so far. May play a role as tumor suppressor. all-trans-retinol + NADP(+) = all-trans-retinal + H(+) + NADPH 5alpha-androstane-3alpha,17beta-diol + NADP(+) = 17beta-hydroxy-5alpha-androstan-3-one + H(+) + NADPH Bound to the endoplasmic reticulum membrane, possibly through a N-terminus anchor. The main bulk of the polypeptide chain was first reported to be facing toward the lumen of the endoplasmic reticulum. However, it was later shown to be facing the cytosol. Belongs to the short-chain dehydrogenases/reductases (SDR) family. DHRS7 was originally reported to be anchored in the endoplasmic reticulum membrane and facing the lumen (By similarity). However, the catalytic moiety was later shown to be facing the cytosol (By similarity).