Crystal structure of 14b bound to Aurora-A at 2.9 Å resolution. (A) The ATP binding site viewed from above. The P-loop has been removed to provide a clear view of the ligand, shown with carbon atoms coloured brown and the surrounding protein, shown with carbon atoms coloured teal. The final 2mFo-DFc electron density map is shown as a wire-mesh, contoured at 1 σ. (B) Side view with the P-loop shown and Ala213, Thr217 residues labelled. (C) Modelling a glutamic acid in position 217 (Glu∗), as found in Aurora-B, leads to steric clashes with the ligand, modelled clash shown as red dashes.