Reaction: 5α-pregnan-3,20-dione + NADP+ = progesterone + NADPH + H+
Other name(s): steroid 5-α-reductase; Δ4-steroid 5α-reductase (progesterone)
Systematic name: 5α-pregnan-3,20-dione:NADP+ 5-oxidoreductase
Comments: Testosterone and 20α-hydroxy-4-pregn-3-one can act in place of progesterone.
Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number: 72412-84-1
References:
1. Cheng, Y.-J. and Karavolas, H.J. Subcellular distribution and properties of progesterone (Δ4-steroid) 5α-reductase in rat medial basal hypothalamus. J. Biol. Chem. 250 (1975) 7997-8003. [PMID: 240847]
2. Cheng, Y.-J. and Karavolas, H.J. Properties and subcellular distribution of Δ4-steroid (progesterone) 5α-reductase in rat anterior pituitary. Steroids 26 (1975) 57-71. [PMID: 1166484]