Figure 2
Effects of alanine substitutions at each of the three charged positions in a KSPRK substrate on relative phosphorylation by Cdk2-cyclin A and Cdk2-Speedy/Ringo A2. The phosphorylation efficiencies of the indicated GST peptides by K2A2coexp, [unP]Cdk2-Speedy/Ringo A2, [pT160]Cdk2-Speedy/Ringo A2, and [pT160]Cdk2-cyclin A were compared. Assays were performed at substrate concentrations of 50 μM. All values are relative to the phosphorylation of the wild type (KSPRK) substrate by the same enzyme. Values represent the means ± S.E. from three separate experiments.