Primary Location: Steroidogenic cells in the adrenal cortex, gonads, and placenta.
Steps Involved:
1. Cholesterol Transport:
Cholesterol is moved from the outer to the inner mitochondrial membrane by the steroidogenic acute regulatory protein (StAR).
2. Initial Conversion:
Cholesterol is converted to pregnenolone by the cytochrome P450 side-chain cleavage enzyme (CYP11A1 or P450scc), the rate-limiting step in steroid hormone synthesis.
3. Steroid Hormone Synthesis:
Pregnenolone is then metabolized into various steroid hormones (glucocorticoids, mineralocorticoids, and sex hormones) through hydroxylation, oxidation, and isomerization.