FIGURE 1.

Principal component analysis of crystallographic Gα structures reveals three major conformations. a, projection of 53 available Protein Data Bank crystal structures of Gα (represented by round points; see also supplemental Table S1) onto the first two principal components (PC) that together account for 65.4% of the total structural variance. Three conformational clusters correspond to GTP-bound (red), GDP-bound (green), and GDI-bound (blue) structures. Projection of conformations sampled from MD simulations under GTP- and GDI-bound conditions are also shown as transparent red- and blue-shaded areas, respectively. b, superimposition of structures with high variance regions (SI, SII, SIII, and LC) colored by conformational cluster.