FIG. 3.

Purified DNA-dependent protein kinase phosphorylates the amino terminus of IκBα. (A) Fractions (17 to 25) from the final mono S FPLC column were subjected to SDS-PAGE and Coomassie staining. (B) Kinase assays were also performed with these column fractions by using a GST-IκBα fusion protein extending from amino acids 1 to 138. (C) These same column fractions were also analyzed by Western blotting using polyclonal goat antibody directed against the DNA-dependent protein kinase catalytic subunit.