Fig. 8. PDKtide is vastly superior to T308tide as a substrate for PDK1 because it interacts with the PIF-binding pocket of PDK1. (A) His-PDK1 was assayed for activity using as substrate the indicated concentration of either PDKtide (▵) or T308tide (○). (B) His-PDK1 was assayed for activity in the presence of PDKtide (25 μM, ▴) or T308tide (100 μM, •) in the presence of the indicated concentrations of PIFtide. The assay was performed in triplicate with <5% difference between the triplicate samples. Similar results were obtained in three separate experiments