3 beta-hydroxysteroid dehydrogenase/Delta 5-->4-isomerase type 1 (3 beta-hydroxysteroid dehydrogenase/Delta 5-->4-isomerase type I) (3-beta-HSD I) (3-beta-hydroxy-5-ene steroid dehydrogenase) (3-beta-hydroxy-Delta(5)-steroid dehydrogenase) (EC 1.1.1.145) (3-beta-hydroxysteroid 3-dehydrogenase) (EC 1.1.1.270) (Delta-5-3-ketosteroid isomerase) (Dihydrotestosterone oxidoreductase) (EC 1.1.1.210) (Steroid Delta-isomerase) (EC 5.3.3.1) (Trophoblast antigen FDO161G)
1_MTGWS 6_ CLVTG 11_ AGGFL 16_ GQRII 21_ RLLVK 26_ EKELK 31_ EIRVL 36_ DKAFG 41_ PELRE 46_ EFSKL 51_ QNKTK 56_ LTVLE 61_ GDILD 66_ EPFLK 71_ RACQD 76_ VSVII 81_ HTACI 86_ IDVFG 91_ VTHRE 96_ SIMNV 101_ NVKGT 106_ QLLLE 111_ ACVQA 116_ SVPVF 121_ IYTSS 126_ IEVAG 131_ PNSYK 136_ EIIQN 141_ GHEEE 146_ PLENT 151_ WPAPY 156_ PHSKK 161_ LAEKA 166_ VLAAN 171_ GWNLK 176_ NGGTL 181_ YTCAL 186_ RPMYI 191_ YGEGS 196_ RFLSA 201_ SINEA 206_ LNNNG 211_ ILSSV 216_ GKFST 221_ VNPVY 226_ VGNVA 231_ WAHIL 236_ ALRAL 241_ QDPKK 246_ APSIR 251_ GQFYY 256_ ISDDT 261_ PHQSY 266_ DNLNY 271_ TLSKE 276_ FGLRL 281_ DSRWS 286_ FPLSL 291_ MYWIG 296_ FLLEI 301_ VSFLL 306_ RPIYT 311_ YRPPF 316_ NRHIV 321_ TLSNS 326_ VFTFS 331_ YKKAQ 336_ RDLAY 341_ KPLYS 346_ WEEAK 351_ QKTVE 356_ WVGSL 361_ VDRHK 366_ETLKS
1: A bifunctional enzyme responsible for the oxidation and isomerization of 3beta-hydroxy-Delta(5)-steroid precursors to 3-oxo-Delta(4)-steroids, an essential step in steroid hormone biosynthesis. Specifically catalyzes the conversion of pregnenolone to progesterone, 17alpha-hydroxypregnenolone to 17alpha-hydroxyprogesterone, dehydroepiandrosterone (DHEA) to 4-androstenedione, and androstenediol to testosterone. Additionally, catalyzes the interconversion between 3beta-hydroxy and 3-oxo-5alpha-androstane steroids controlling the bioavalability of the active forms. Specifically converts dihydrotestosterone to its inactive form 5alpha-androstanediol, that does not bind androgen receptor/AR. Also converts androstanedione, a precursor of testosterone and estrone, to epiandrosterone (PubMed:1401999, PubMed:2139411). Expected to use NAD(+) as preferred electron donor for the 3beta-hydroxy-steroid dehydrogenase activity and NADPH for the 3-ketosteroid reductase activity (Probable)