Fig. 1. The distinction between the inactive and fully active AT₁ receptor crystal structures.

A The overall structure of the inactive AT₁ receptor in complex with an antagonist ZD7155 (green) and b₅₆₂RIL (yellow). B The overall structure of the fully active AT₁ receptor in complex with a partial agonist S1I8 (magenta) and a G protein mimetic nanobody (cyan). C Major conformational changes between the inactive (blue) and fully active (orange) AT₁ receptor. Red arrows show obvious transmembrane (TM) movements during activation. The zoom-in views represent the distance between the Cα atoms of L^5.55 and N^7.46 and the angle among the Cα atoms of F^6.34, S^6.47, and V^2.41, in order to monitor the conformational rearrangements of TMs 5–7. The superscripts refer to the Ballesteros–Weinstein numbering system. All structure figures were drawn by PyMOL. AT₁R angiotensin II type 1 receptor, S1I8 S1I8 mutant angiotensin II, Nb Nanobody, TM transmembrane helices, H8 helix 8.