Figure 4.

(A) Effect of DNA-binding domain-derived peptides on p53 phosphorylation. GST-p53^1–393 was subjected to solid-phase kinase reaction with WCE, in the presence of peptides 7–9 before addition of [γ³²P]ATP (A lanes), before and during kinase reaction (B lanes), or only with the addition of [γ³²P]ATP (C). Lower bands represent staining of the GST-p53 to indicate equal loading. (B) Effect of peptides on phosphorylation of p53 by PKA and WCE. GST-p53^1–393 was subjected to solid-phase phosphorylation (i.e., washes performed before addition of ATP; lanes C and 7–9) or with [γ³²P]ATP added without intermediate washes (lanes A and 7*) by PKA or WCE, respectively, in the presence of indicated peptides. (C) Effect of P7 on p53 phosphorylation by CKIIβ, PKA, and WCE. GST-p53 subjected to solid-phase kinase reaction in the presence of P7 and kinases.