Fig. 2.

(A) The high-affinity βarr2-pp-μOR-morphine complex immersed in the membrane bilayer. (B) Strong interactions between the N-terminal domain of βarr2 and the pp-C tail of the μOR, mostly involving pS and pT residues on the pp-C tail interacting with positively charged residues on the N-terminal domain of βarr2. (C) The membrane anchoring from the C edge of βarr2, which is dominated by hydrophobic contacts. Here, the P atoms are shown by orange spheres. (D) The polar anchor from βarr2 to ICL2 of the μOR, which creates a polar network of interactions from the finger loop to ICL2 and the cytosolic end of TM2. (E) Polar anchors from the βarr2 to both ICL3 and the bottom end of TM6, fully engaging the body of the βarr2 to the core of the μOR.