The predicted lipid-binding site of Vinculin. The coordinates of vinculin (PDB 1ST6) are displayed with the predicted lipid-binding sites colored yellow (residues 935–978) and brown (residues 1020–1040). Phosphatidylinositol 4,5-bisphosphate appears to bind to a basic "collar" surrounding the carboxyl-terminal arm (residues 910, 911, 1039, 1049, 1060, 1061), and a basic 'ladder' along the edge of helix 3 (residues 944, 945, 952, 956, 963, 966, 970, 978, 1008, and 1049). These residues are shown in gold. Note: the overlap of the computationally derived site and the experimentally discovered phosphatidylinositol site. Amino and carboxyl termini are indicated in blue and red, respectively. Residues 856 through 874 are disordered in the vinculin electron-density map and are not shown, the start (residue 855) and stop site (residue 874) for this region are shown in green. (a) Ribbon model, (b) Space-filling representation, and (c) Electrostatic field potentials (orientation of the protein is identical to that viewed in (a) and (b)). The colors red, white and blue are used to indicate negative, neutral and positive sfield potentials (c), respectively.