Hedgehog precursor protein cholesterolysis. Autoprocessing begins with the central “HINT” domain’s first residue, cysteine, rearranging the adjacent amide bond to form a thioester. In step two, the C-terminal subdomain (dark gray) activates bound cholesterol for attack at the activated acyl group. Finally, the N-terminal domain, which possesses cell signaling activity, dissociates with its newly formed carboxy terminus esterified to cholesterol.