Pregnenolone is dehydrogenated to form pregn-5-ene-3,20-dione

Stable Identifier
Reaction [transition]
Homo sapiens
Pregnenolone + NAD+ => pregn-5-ene-3,20-dione + NADH + H+
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Pregnenolone and NAD+ react to form pregn-5-ene-3,20-dione and NADH + H+. This reaction is catalyzed by the 3 beta-hydroxysteroid activity of 3-beta-hydroxysteroid dehydrogenase/isomerase (HSD3B) enzyme associated with the endoplasmic reticulum membrane. The active form of the enzyme is a homodimer. The enzyme occurs in two isoforms that are similar in their biochemical properties but differ in their tissue expression: type I (HSD3B1) is found in placenta and skin, while type II (HSD3B2) is found in the adrenal glands and gonads.
Literature References
PubMed ID Title Journal Year
2770297 Human placental 3 beta-hydroxy-5-ene-steroid dehydrogenase and steroid 5----4-ene-isomerase: purification from mitochondria and kinetic profiles, biophysical characterization of the purified mitochondrial and microsomal enzymes

Strickler, RC, Myers, RP, Thomas, JL

J Steroid Biochem 1989
1944309 Structure and expression of a new complementary DNA encoding the almost exclusive 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4-isomerase in human adrenals and gonads

Simard, J, Rheaume, E, de Launoit, Y, Lachance, Y, Breton, N, Luu-The, V, Labrie, F, Trudel, C, Dumont, M, Zhao, HF

Mol Endocrinol 1991
12832414 Structure/function relationships responsible for coenzyme specificity and the isomerase activity of human type 1 3 beta-hydroxysteroid dehydrogenase/isomerase

Duax, WL, Brandt, S, Norris, W, Addlagatta, A, Fuller, RR, Thomas, JL

J Biol Chem 2003
2243100 Characterization of human 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4-isomerase gene and its expression in mammalian cells

Simard, J, de Launoit, Y, Lachance, Y, Luu-The, V, Labrie, F, Leblanc, G, Dumont, M, Labrie, C, Guerin, S

J Biol Chem 1990
Catalyst Activity

3-beta-hydroxy-delta5-steroid dehydrogenase activity of HSD2B1 dimer, HSD3B2 dimer [endoplasmic reticulum membrane]

Orthologous Events
Cross References
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