5alpha-pregnane-3,20-dione

1. 5alpha-pregnane-3,20-dione:NADP+ delta4-oxidoreductase

Catalysed by SRD5A1, SRD5A2, SRD5A3cytosol

1. 3alpha-hydroxy-5alpha-pregnan-20-one:NADP+ 3-oxidoreductase (A-specific)

Catalysed by AKR1C4, AKR1C3, AKR1C2, AKR1C1cytosolOne of 3 routes

1. 5alpha-pregnane-3,20-dione + NADPH + H(+) = 20alpha-hydroxy-5alpha-pregnane-3-one + NADP(+)

Catalysed by AKR1C4, AKR1C2, AKR1C1

1. 5alpha-pregnane-3,20-dione:NADP+ delta4-oxidoreductase
2. progesterone + reduced [NADPH--hemoprotein reductase] + O2 = 16alpha-hydroxyprogesterone + oxidized [NADPH--hemoprotein reductase] + H2O + H(+)

Catalysed by SRD5A1, SRD5A2, SRD5A3, CYP3A4 and 1 morecytosol

1. 5alpha-pregnane-3,20-dione:NADP+ delta4-oxidoreductase
2. cytochrome P450 (progesterone)

Catalysed by SRD5A1, SRD5A2, SRD5A3,

1. 5alpha-pregnane-3,20-dione:NADP+ delta4-oxidoreductase
2. cytochrome P450 (progesterone)
3. cytochrome P450 (17alpha-hydroxyprogesterone)

Catalysed by SRD5A1, SRD5A2, SRD5A3, CYP17A1cytosol, endoplasmic reticulum

1. 5alpha-pregnane-3,20-dione:NADP+ delta4-oxidoreductase
2. cytochrome P450 (progesterone)
3. (17R,20S)-17,20-dihydroxypregn-4-en-3-one + NAD(+) = 17alpha-hydroxyprogesterone + NADH + H(+)