Fig. 2. Active conformation of the FPR2-WKYMVm complex.

a The movement of helix VI. The transmembrane helical bundles in the structures of FPR2-WKYMVm (cyan), μOR-BU72 (pink, PDB code: 5C1M) and μOR-naloxone (dark red, PDB code: 4DKL) are shown in cartoon representation at an intracellular view. The red arrows indicate the movements of helices V, VI, and VII in the FPR2-WKYMVm and μOR-BU72 (active) structures relative to the μOR-naloxone (inactive) structure. b The hydrogen bond interaction between R^3.50 and Y^5.58 in FPR2. The FPR2 residues R^3.50 and Y^5.58 are shown as cyan sticks. The inactive A₁AR-DU172 structure (PDB code: 5UEN) is shown in yellow cartoon representation. The A₁AR residues R^3.50 and E^6.30 that form a salt bridge are shown as yellow sticks. The polar interactions are shown as green dashed lines. c The conformational change of W^6.48. The structures of FPR2-WKYMVm (cyan), μOR-BU72 (pink), and μOR-naloxone (dark red) are shown as cartoons. The residue W^6.48 in the three structures is shown as sticks. The red arrow indicates the movement of W^6.48 side chain in the FPR2-WKYMVm and μOR-BU72 (active) structures relative to the μOR-naloxone (inactive) structure. d The conformational change of the P^5.50I/V^3.40F^6.44 motif. The residues at positions 3.40, 5.50, and 6.44 in the structures of FPR2-WKYMVm (cyan), μOR-BU72 (pink), and μOR-naloxone (dark red) are shown as sticks. The red arrows indicate the relocations of these residues in the FPR2-WKYMVm and μOR-BU72 (active) structures relative to the μOR-naloxone (inactive) structure.