Figure 3

Analysis of FIP200-COP1 interaction by Split GFP assay. (A) 293T cells were transfected with expression vectors encoding COP1 (wild type (WT) and phosphorylation-defect mutant (SA)) and FIP200 fused with N-terminal (YN) and C-terminal (YC) halves of YFP. Cell lysates were analyzed by Western blotting using antibody against FIP200. (B, C) NIH3T3 cells were transfected with expression vectors encoding N-terminal (YN) and C-terminal (YC) halves of YFP alone and fused with COP1 (wild type and SA mutant) and FIP200. Before and after treatment with UV, GFP signals were observed using phase-contrast and fluorescence microscopy (B) and measured with a flow cytometer (C). Higher magnification of photos of FIP200-COP1 and COP1-COP1 interactions are also shown (B, right panels). *; not significantly different (C).