Figure 1.

Structure of K-Ras. A, structure of K-Ras4B (G12V, 1–169) is shown in ribbon representation with lobes, nucleotide, and switch regions highlighted as follows: lobes 1 and 2, as well as the switch regions shown in cyan, green, and dark orange, respectively. The bound GTP is shown in stick representation and the Mg²⁺ ion as a cyan sphere. B, sequence alignment of the HVR domains of K-Ras, H-Ras, and N-Ras (formally starting at 167/170), with posttranslational lipid modifications, but not carboxy-methyl truncations indicated. Pal and Far refer to palmitoylation and farnesylation sites, respectively.