Figure 6. Stability effect of alanine mutation of the residues involved in the activation and stabilization clusters.

a-d, Effect on stability of mutation of the residues involved in the activation cluster I (a), stabilization clusters II (b) and III (c), and the inter-domain interface (d) on the GDP- and receptor-bound states. Orange: mutations that dramatically destabilize the GDP-bound state, but do not affect the stability of receptor-bound state; forest green: mutations that do not destabilize the GDP-bound state, but significantly destabilize the receptor-bound state; black: mutation that destabilize both nucleotide- and receptor-bound states. The alanine mutants represented by the orange and the forest green box correspond to the colour of residue number shown in Fig. 5a-b and Fig. 7a-b. The blue wavy box cartoons represent the nucleotide- or receptor-bound states affected by mutations.