FIG. 1.

Coomassie brilliant blue-stained polyacrylamide gels of Flag antibody immunoprecipitates (Flag-IP) from BJAB B lymphoblasts that were stably converted to FLP expression (lane marked BFLP) or from negative-control BJAB B lymphoblasts (lane marked B). Cells were lysed in nonionic detergent, and extracts were immunoprecipitated using M2 Flag antibody-coupled beads. Proteins bound to the beads were eluted in SDS sample buffer; resolved in 6.5, 7.5, or 12% polyacrylamide gels; and stained with Coomassie brilliant blue. FLP and Hsp72/Hsc73 were confirmed by immunoblotting. Other proteins of >250, 95, 65, 55, 53, and 30 kDa that were consistently present in immunoprecipitates from FLP-expressing BJAB cells and absent in control immunoprecipitates from nonexpressing BJAB cells—designated I, II, III, IV, V, and VI—were excised from the gels and identified by amino acid sequence. MW, molecular weight, markers (in thousands).