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Biosynthesis of Progesterone

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In mammals, the binding of FSH (Follicle-Stimulating Hormone), LH (Luteinizing Hormone) or ACTH (Adreno Cortico-Trophic Hormone) to their receptors at the adrenal cortex, ovary or testes membranes starts a G-Protein mediated reaction sequence. This leads to a transport of cholesterol from cytoplasmic inclusion droplets into the mitochondria, assisted by SCP (Sterol Carrier Protein). Cholesterol is biosynthesized in many tissues and is a precursor to all steroid hormones. Altering a side chain or subsistent group of a cholesterol molecule produces various steroids molecules.  Steroids have a classical pathway for which they are formed. Pregnenolone and progesterone are both molecules that are derived from cholesterol.  The conversion of cholesterol to pregnenolone is effected by the trifunctional complex cholesterol monooxygenase, which is located [...]


1.Contact sites from human placental mitochondria: characterization and role in progesterone synthesis.
Uribe A, Strauss JF 3rd, Martinez F.
Arch Biochem Biophys. 2003 May 15;413(2):172-81.
2.Molten globule structure and steroidogenic activity of N-218 MLN64 in human placental mitochondria.
Tuckey RC, Bose HS, Czerwionka I, Miller WL.
Endocrinology. 2004 Apr;145(4):1700-7. Epub 2004 Jan 08.
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