Instead of turning on a gene when a key is inserted into the CAR receptor, the gene turns off.
Hormone receptors are proteins that help regulate gene function.
Usually a receptor becomes activated or turned on when a specific hormone, or ligand, inserts itself into the receptor. The ligand acts like a key that unlocks the receptor. CAR is already running, turning on genes when the key is missing. And the receptor gets turned off when the key is inserted. The key for this CAR is a steroid, androstanol.