The β1-adrenergic receptor (β1AR) contains empty cavities in its preactive conformation, which disappear in the active one. Now, using X-ray crystallography of xenon-derivatized β1AR crystals, a cavity has been shown to be in contact with the cholesterol-binding pocket. Monitoring the binding of a cholesterol analogue in solution has explained the function of cholesterol as a negative allosteric modulator of β1AR.
Filling of a water-free void explains the allosteric regulation of the β1-adrenergic receptor by cholesterol