FIGURE 1.
GIV is a multi-modular protein that activates Gαi via its C-terminal GEF motif by assembling a unique GIV-Gαi protein-protein interface. A, schematic representation of the domain organization of GIV. MT, microtubule; GBD, GTPase-binding; PI4P, phosphatidylinositol 4-phosphate; NT, N terminus; CT, C terminus. B, left, homology model of the GEF sequence of GIV (orange) bound to Gαi3 (blue, green, and red) generated as described in Ref. 30. Green denotes the switch II (SwII) region, and red denotes the α3 helix. Right, same view as is the left panel with a space-filling surface representation of Gαi3 colored by hydrophobicity (red to blue scale indicates increasing hydrophobicity). Three hydrophobic residues in GIV (Leu-1682, Phe-1685, and Leu-1686) are predicted to dock onto a hydrophobic cleft on Gαi3.