Figure 3. Comparison of active and inactive β₂AR structures.

a, Side and cytoplasmic views of the β₂AR-Gs structure (green) compared to the inactive carazolol-bound β₂ AR structure ³ (blue). Significant structural changes are seen for the intracellular domains of TM5 and TM6. TM5 is extended by two helical turns while TM6 is moved outward by 14 Å as measured at the α-carbons of Glu268 (yellow arrow) in the two structures. b, β₂AR-Gs compared with the nanobody-stabilized active state β₂AR-Nb80 structure ¹² (orange). c, The positions of residues in the E/DRY and NPxxY motifs and other key residues of the β₂AR-Gs and β₂AR-Nb80 structures. All residues occupy very similar positions except Arg131 which in the β₂AR-Nb80 structure interacts with the nanobody. d, View from the cytoplasmic side of residues shown in (c).