AMBOSS directly states it here “A mitochondrial enzyme that catalyzes the conversion of cholesterol to pregnenolone, which is the first step in steroid hormone synthesis. Activated by ACTH and inhibited by ketoconazole.”
https://next.amboss.com/us/search?q=cholesterol+desmolase&v=overview
Added #deck-AnKing Overhaul for Step 1 & 2-AnKingMed, rejected-suggestion and removed #deck-anking-overhaul-for-step-1–2-ankingmed, open-suggestion