Figure 5.

Nucleoside binding pockets of (A) APH(3′)-IIIa (1L8T) with ADP (cyan), (B) APH(2″)-IVa (4DT9) with guanosine (orange), and (C) APH(9)-Ia (3I0Q) with AMP (green). The binding modes of the nucleotide substrate and an ePK inhibitor [(A,C) CKI-7, (B) quercetin] are compared. For each panel, the gatekeeper residue and two hinge residues that form the ATP/GTP binding template are highlighted in blue stick representation. Hydrogen-bonding interactions between the hinge and the substrate are shown as black dotted lines and those between the hinge and the inhibitor are shown as gray dotted lines. The black arrows point to a hydrophobic back pocket in each binding site that is not normally occupied by the nucleotide substrate.