Figure 3.

Interaction of the ATF3 and p53 proteins is required for stabilization of the tumor suppressor. (A) GST-ATF3 fusion proteins were adsorbed to glutathione-agarose, and incubated with in vitro-translated [³⁵S]methionine-labeled p53 protein. After extensive washes, the bound p53 was eluted, subjected to SDS–PAGE and visualized by fluorography. (B) GST or GST fused to the mutant (Δ102–139) or full-length ATF3 protein (1–181) was adsorbed to glutathione-agarose, incubated with in vitro-translated [³⁵S]methionine-labeled ATF3 protein (full length) and subjected to pulldown assays as in (A). (C) Plasmids encoding p53, the full-length ATF3 protein or mutant ATF3 protein (Δ102–139) were transfected where indicated with 0.05 μg pEGFP-N1 into H1299 cells and Western blotting performed as described in Figure 1A with the exception that the HA-tagged ATF3 proteins were detected with an anti-HA antibody.