Chapter 29

Fig. 29.3 Superposition of the crystal structures of the β1-adrenergic receptor with the agonists isoprenaline 29.5 (red-brown) and the antagonists cyanopindolol 29.6 (green). The agonist forms an H-bond to Ser211 and Ser215 and the binding pocket contracts because helices H5 and H1 lean in by about 1 Å. This helix movement leads to activation of the receptor.