Fig. 3: Hydrophobic interactions between ETBR and NK1R in the active state.
From: Structure of endothelin ETB receptor–Gi complex in a conformation stabilized by unique NPxxL motif
Hydrophobic interactions around R3.50 and L/Y7.53 of ETBR (a, b) and NK1R (c, d), respectively. a The downward motion of TM7 of ETBR is stabilized by N3827.49 and L3867.53 in the NPxxL motif through a series of hydrophobic interactions with I1402.43, L1953.46, etc. The density around all rendered residues at a contour level of 5.0 σ is shown as a mesh. b The large hydrophobic side chains of L348H5.20 and L353H5.25 of Gαi penetrate deeply into the hydrophobic pocket formed by TM3, TM5, TM6, and TM7 of ETBR. I343H5.15 and I344H5.16 form additional interactions with ICL2. The density around the rendered residues of the α5 helix of Gαi is shown as a mesh at a contour level of 5.0 σ. c The downward motion of TM7 of NK1R is stabilized by E782.50, N3017.49, and Y3057.53 in NPxxY through a series of hydrogen-bond interactions as well as hydrophobic interactions with L712.43, V1263.46, etc. d The large hydrophobic side chains of L353H5.20 and L358H5.25 of Gαq penetrate deeply into the hydrophobic pocket formed by TM3, TM5, TM6, and TM7 of NK1R. Identical residues among Gi, Go, and Gs are denoted by “*” before the amino acid label, but a conserved residue (L348H5.15 of Gαq) in d was omitted because it does not contact the receptor. The NPxxL motif leads to the formation of a larger cavity than NPxxY (indicated by a dashed oval).
