Hydrogen bond network associated to C6.47 in both inverse-agonist (left) and agonist (right) bound structures of β
AR (A) and bRho (B). Panel A: C6.47 hydrogen bonds N7.45 which retains N7.49, avoiding interaction of the latter with D2.50 (left). Breaking of C6.47-N7.45 interaction releases (right) N7.49 permitting its interaction with D2.50. Panel B: the release of both C6.47-T7.44 and Y7.48-N7.49 hydrogen bonds (left), permits N7.49 to form a hydrogen bond with D2.50. Helices are colored as follows: TM1:white, TM2:gold, TM3:red, TM6:blue and TM7:pale-red. The remaining helices have been omitted for better clarity. Relevant side-chains are shown as sticks (cyan) and hydrogen bonds are indicated by dashed lines. A crystallographic water molecule is shown as spheres.