Figure 3.

Specific binding between mE2 and IκBα. (A) ³⁵S-labeled mouse IκBα protein was coimmunoprecipitated with ³⁵S-labeled mE2 protein in vitro by anti-mE2 sera. Equal amounts of protein were loaded in each lane. Coimmunoprecipitation with preimmunesera, anti-mE2 sera, and mE2 peptide competition are shown in lanes 1, 2, and 3, respectively. (B) ³⁵S-labeled mE2 or mE2* protein binding to GST-mIκBα in GST-pulldown assay using dithiobis-succinimidylpropionate, a reversible crosslinker. Ten percent of the in vitro-translated mE2 or mE2* protein was loaded on lanes 1 and 4. Radioactivities were analyzed by PhosphoImager.