Dehydrogenase/Reductase SDR Family, Member 9 (DHRS9)

The deduced 319-amino acid protein has a calculated molecular mass of 35 kD. DHRS9 contains 4 motifs conserved in most short-chain alcohol dehydrogenase/reductase family members. Northern blot analysis of primate tissues detected DHRS9 in trachea, colon, tongue, and esophagus, but not in heart, kidney, liver, lung, stomach, small intestine, or spleen. In situ hybridization and immunohistochemical staining localized DHRS9 to ciliated cells in surface epithelium in primate airway and lung and in superficial layers of human esophagus.It was most efficient as a 3-alpha-hydroxysteroid dehydrogenase, converting 3-alpha-tetrahydroprogesterone to dihydroprogesterone and 3-alpha-androstanediol to dihydrotestosterone with similar catalytic efficiency. DHRS9 showed much lower activity toward retinol substrates.