Figure 4.

Complete invasion of the receptor’s cytosolic binding pocket by a zwitterionic lipid. (A) Probability density map of (black, labeled P) the phosphorus atom of the bound phospholipid and (cyan, labeled 1–7) transmembrane helices viewed from the cytosol in a single 14-μs simulation initiated from the G-protein-derived structure. Each helix is represented by four C_α atoms near the headgroup region of the bilayer’s cytosolic leaflet (see Supporting Materials and Methods). (B) Time trajectories of H6 splaying, d_H3–H6, ionic lock formation, d_lock, and R3.50 binding for the single identified lipid, d_R3.50-lipid. Ordinate units are nm. (C–F) Cytosolic view of representative conformations from time points noted in (B). This simulation is depicted in Movie S3. Corresponding data for another 3-μs simulation in which a lipid dissociated from the receptor’s annular lipids and moved completely into the receptor’s cytosolic binding pocket are provided in Fig. S6. To see this figure in color, go online.