Figure 2.

(a) Surface view of the Cdc25A crystal structure (PDB id: 1C25) [20] with the catalytic Cys430 in the HCX₅R loop (Cdk representation) and the C/N terminal tails highlighted. (b) Surface view of the Cdc25B crystal structure (PDB id: 1QB0) [21] with the catalytic HCX₅R loop, the water molecules of the “swimming pool” region (yellow dots), the C-terminal helix, and the N-terminal tail highlighted. On the right, special focus is given to several of the most important residues (thick tube representation) within the catalytic pocket and the “swimming pool” involved in the catalytic process and the interactions with ligands.