Figure 3.

G3BP BC domain inhibits arsenite-induced assembly of SGs. (A) Cos cells were transiently transfected with GFP-BC, GFP-ABC, or GFP-BCD, treated with arsenite before fixation, and double stained with fluorescent oligo-dT probe (red). GFP, green. Arrows indicate transfected cells expressing GFP fusion. (B) Equal amounts of whole-cell extracts prepared from metabolically labeled CCL39 cells were immunoprecipitated with anti-G3BP antibody. Proteins were revealed by immunoblot analysis using the same antibody. S, supernatant; IP, immunoprecipitation. (C) Phosphotryptic peptide mapping of immunopurified ³²P-labeled G3BP, shown in A, from untreated (left) and arsenite-treated (right) CCL39 cells. The identification of phosphorylation sites Ser 149 and Ser 232 was previously reported (Tourrière et al., 2001). (D) The intensity of each spot from untreated (blue) and arsenite-treated (red) was quantitated by densitometry scanning of the chromatography plates using ImageQuant™ software version 5.2. Error bars resulting from two independently performed experiments are shown.