Reduction of androstenedione to testosterone Authored: Jassal, B, 2008-10-01 13:18:42 EC Number: 1.1.1.63 Edited: Jassal, B, 2007-04-20 21:09:56 Pubmed2197970 Pubmed8075637 Pubmed8547185 Pubmed9536209 Reactome Database ID Release 43193064 Reactome, http://www.reactome.org ReactomeREACT_9948 Reviewed: D'Eustachio, P, 2007-04-20 21:11:21 The 17HSD family of enzymes catalyze the final step in the synthesis of estradiol and testosterone. They convert inactive 17-ketosteroids to their active 17beta-hydroxy forms. Androstenedione, a ketosteroid, is reduced to testosterone, a highly potent androgen, by the enzyme 17beta-hydroxysteroid dehydrogenase isoform III (17HSD3). The other human isoforms of 17HSDs to take part in the final steps of active steroid biosynthesis are types 1 and VII, which reduce estrone to estradiol.<br>Corticotropin (Adrenocorticotropic hormone, ACTH) acts through the ACTH receptor called melanocortin receptor type 2 (MC2R) to stimulate steroidogenesis, increasing the production of androgens (McKenna et al, 1997).<br>In males, Lutropin (LH) stimulates testosterone production.