FIGURE 1.

TRIM33 interacts with ALC1 upon induction of DNA damage. A, HEK293 cells expressing either vector or FLAG-ALC1 were treated with either vehicle or bleomycin, subjected to immunoprecipitation using FLAG beads, and then processed by LC-MS/MS. The relative peptide counts for each condition are shown for ALC1, PARP1, APLF, histone H2B, Ku70, and TRIM33. As shown, TRIM33 peptides were identified only in the bleomycin-treated samples. B, endogenous interaction of TRIM33 and ALC1 upon hydroxyurea (HU) and bleomycin treatment. DNase-treated nuclear extracts from untreated (Un) cells or cells treated with HU (3 mm, 3 h) or bleomycin (300uM, 1 h) were immunoprecipitated with anti-TRIM33 antibody. Immunoprecipitates were processed for Western blotting (WB) using antibodies to TRIM33 and ALC1 (top two panels, IP). Aliquots of nuclear extract were also directly processed for Western blotting with these antibodies (bottom two panels, Inputs).