Identification of Ikaros family proteins as IRF4 complex components in B1-8hisplenic B cells. B1-8hi splenic B cells were stimulated for 72 hours, and whole cell extracts were immunoprecipitated with control immunoglobulin (IgG) or anti-IRF4 (α-IRF4) antibodies. (A) Sodium dodecyl sulfate–polyacrylamide gel electrophoresis analysis and MeOH-free Coomassie Brilliant Blue staining. IRF4 complex components were indicated at expected molecular weight. (B) LC-MS/MS analysis of the IRF4 complex. IRF4 complex components were determined as specific detection with α-IRF4, or more than twofold protein score with α-IRF4 than control IgG. Selected IRF4 complex components were shown with protein score and number of unique peptide from 3 independent experiments. (C) Immunoprecipitation followed by immunoblot analysis of indicated IRF4 complex components. Input, 2% of whole cell extracts. Data are representative of 1 of 3 (A) or 1 of 2 (C) independent experiments. n.d., not detected.
