FIGURE 7. Inhibition of JNK phosphorylation of transcription factors c-Jun and ATF2 with D-site peptides from MKK7.

A, D-site peptides (triangle) were used to inhibit JNK1 or JNK2 phosphorylation of c-Jun or ATF2. B and C, purified GST-c-Jun (1 µm) was incubated with purified active JNK1 (2.5 nm) and [γ-³²P]ATP for 20 min in the absence or presence of the specific concentrations of the indicated peptides (see Table 3). B, results are plotted as percent phosphorylation relative to that observed in the absence of any added peptide. Phosphate incorporation into c-Jun was analyzed by SDS-PAGE and quantified on a PhosphorImager. Data are the average of at least two experiments, with duplicate or triplicate data points in each experiment. C, shown is an autoradiogram of a representative experiment. D and E, as for B and C, respectively, with the exception that the substrate was purified GST-ATF2 (1 µm). F and G, as for B and C, except the kinase was JNK2 (5 nm). H, as for D, except the kinase was JNK2.