FIG 4.

Gag is sufficient to traffic to stress granules in uninfected cells. MMTV Gag containing a C-terminal GFP tag (2) (A) was coexpressed with myc–YB-1, GFP-G3BP1, or YFP–TIA-1 (B) in uninfected NMuMG cells. Colocalization color maps were generated as described above and are shown in the far right column. A dashed white line drawn around the perimeter indicates the outline of the cell shown in the colocalization color-mapping image. (C) Uninfected or MMTV-infected NMuMG cells were transfected with myc–YB-1 and fixed for immunofluorescence 18 h after transfection. MMTV Gag was detected using anti-CA antibody (green), and YB-1 was detected using anti-YB-1 antiserum (red). Cells were scored for the presence or absence of YB-1-containing cytoplasmic granules. (D) Uninfected or RSV-infected QT6 cells were transfected with plasmids expressing myc–YB-1 (uninfected) or myc–YB-1 and Gag-GFP (RSV infected). Cells were evaluated for YB-1 staining in cytoplasmic granules. Statistical analysis of the data shown in panels C and D was determined using Fisher's exact test (GraphPad Prism). NS, nonsignificant (P > 0.05); ***, P < 0.0001. Data were derived from >30 cells from at least two experiments conducted on separate days.