FIG. 7.

DNA-PK associates with IκBα. (A) HeLa S100 extract was incubated with a variety of GST-IκBα fusion proteins bound to glutathione agarose beads, followed by Western blot analysis with DNA-PKcs antibody. HeLa S100 extract with 50% of the input shown (lane 1) was incubated with either GST alone (lane 2), GST–wild-type IκBα (lane 3), GST-IκBα with mutations at serine residues 32 and 36 (lane 4), GST-IκBα with its amino terminal 53 amino acids deleted (lane 5), GST-IκBα containing the amino-terminal 138 amino acids of IκBα (lane 6), or GST-IκBα containing the amino terminal 53 amino acids of IκBα (lane 7). Western blot analysis was performed with a goat polyclonal antibody directed against DNA-PKcs. (B) The GST-IκBα fusion proteins used in panel A were subjected to SDS-PAGE and Western blot analysis with antibody directed against GST.