Fig. 5.

Predicted orientations of Gβγ complexes at phospholipid bilayers. (A) The GRK2-Gβγ complex in a likely membrane orientation, with the expected membrane plane running along the bottom of the box. The receptor docking site of GRK2 was homology modeled based on the structure of GRK6 (PDB entry 3NYN). The small tilt angle suggested by our SFG measurements prevents this newly crystallized region from colliding with the lipid bilayer. (B) The Gαβγ heterotrimer modeled in the same orientation, using Gβγ for alignment. The Gα subunit is shown in blue, and in this orientation it would maintain reasonable contacts with the lipid bilayer.