Side chain cleavage of 17alpha-hydroxypregnenolone to yield DHA

Stable Identifier
R-HSA-193070
Type
Reaction
Species
Homo sapiens
Compartment
Synonyms
17alpha-hydroxyprenenolone + NADPH + H+ + O2 => DHA (dehydroepiandrostenedione) + NADP+ + H2O + acetaldehyde
Locations in the PathwayBrowser
Summation

17-alpha-hydroxypregnenolone, NADPH + H+, and O2 react to form DHA (dehydroepiandrostenedione), NADP+, H2O, and acetaldehyde. CYP17 (which also catalyzes 17-alpha-hydroxylation) catalyzes this lyase reaction. There are marked species differences in which substrate is used for this lyase activity. The human enzyme prefers 17alpha-pregnenolone (delta5 steroid) as substrate (Brock, BJ, Waterman, MR, 1999). 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).

Literature References
PubMed ID Title Journal Year
10406467 Molecular modeling of human P450c17 (17alpha-hydroxylase/17,20-lyase): insights into reaction mechanisms and effects of mutations

Auchus, RJ, Miller, WL

Mol Endocrinol 1999
9536209 A critical review of the origin and control of adrenal androgens

McKenna, TJ, Fearon, U, Clarke, D, Cunningham, SK

Baillieres Clin Obstet Gynaecol 1997
Participants
Participant Of
Catalyst Activity
Catalyst Activity
Title
steroid 17-alpha-monooxygenase activity of CYP17A1 [endoplasmic reticulum membrane]
Physical Entity
Activity
This entity is regulated by
Positive Regulation
Orthologous Events
Authored
Reviewed