Catalyzes the conversion of 17-oxosteroids to 17beta-hydroxysteroids ( , ). Favors the reduction of androstenedione to testosterone ( ). Testosterone is the key androgen driving male development and function . Uses NADPH while the two other EDH17B enzymes use NADH ( ). Androgens such as epiandrosterone, dehydroepiandrosterone, androsterone and androstanedione are accepted as substrates and reduced at C-17 . Can reduce 11-ketoandrostenedione as well as 11beta-hydroxyandrostenedione at C-17 to the respective testosterone forms (, ).
Subcellular locations: Endoplasmic reticulum
Testis.