The allosteric coupling between ligand and activation loop is dominated by four low energy modes. The allosteric coupling between the PS48 ligand and the activation loop in the large lobe of PDK1 is due to the four low energy modes 7, 8, 9 and 11. The deformations in the activation loop and the ligand are shown in blue in A, B, C and D on top of the crystal backbone structure in grey. The allosteric profile for the coupling modes and the rest of the modes is shown in E. The modes 7, 8, 9 and 11 show a clear dominant peak at ARG238 in the large lobe, black curve. The allosteric profile without these modes is shown in grey and here the coupling is lost.