Decreased cytochrome c oxidase IV expression reduces steroidogenesis.

Steroidogenic acute regulatory protein facilitates the translocation of cholesterol to the inner mitochondrial membrane, thereby initiating steroidogenesis. At the inner mitochondrial membrane, cytochrome P450 side-chain cleavage enzyme converts cholesterol to pregnenolone, an oxidative process requiring electrons from NADPH. Pregnenolone then serves as the substrate for the formation of progesterone or dehydroepiandrosterone by downstream enzymes.