Figure 3.

X-ray structural analysis of Ras(T355S) in the GppNHp-state. (A) Superimposition of the structures (in worm plot) of wild-type Ras (Protein Data Bank ID code 5p21) in blue and molA of Ras(T35S) in red. Neither switch I nor II of the mutant is visible. (B) Part of the final 2F_o − F_c map at 1.2 σ with the Ras(T35S) model (molecule C in the asymmetric unit) as a stick molecule and with the three phosphates of GppNHp in purple and Mg²⁺ as a ball in magenta, as indicated. The effector region from Tyr-32 to Glu-37, including Ser-35, is not visible. The corresponding region from the wild-type Ras⋅GppNHp structure (45) is shown in green, with corresponding residues as indicated.