Fig. 1

GRI and GRIII boxes of PFV Gag are Nucleolar Localization Signals. a Scheme of PFV Gag protein where the primary protease-cleavage site at residue 621 is indicated by a dotted line. Some characterized motifs are shown. CTRS: cytoplasmic targeting and retention signal (aa 43–60); NES: nuclear export signal (aa 95–112); dim: dimerization domain (aa 130–160); GRI, GRII and GRIII: glycine-arginine rich box I (aa 485–511), II (aa 534–557) and III (aa 586–618); CBM, chromatin-binding motif (aa 536–544). b The subcellular localization of GRI, GRII, GRII_R540A or GRIII expressed as GFP-fusion proteins in fixed HeLa cells was analyzed 24 h post-transfection by immunofluorescence and confocal microscopy. Nucleoli were immune-stained with an anti-nucleolin antibody (ab 22758, Abcam, 1:800) and nuclei were stained with DAPI (blue). c The localization of GFP-GRI expressed in HeLa cells relative to the NoLS of HIV-1 Rev protein (aa 35–51) in fusion with DsRed or specific markers of the nucleolar subcompartments was studied as in B. Cells were stained with antibodies against fibrillarin (c13c3, Cell signaling, 1:200), B23 (sc6013_R, Santa Cruz, 1:200) or UBF (H300, Santa Cruz, 1:200) to visualize the dense fibrillar component (DFC), the granular component (GC) and the fibrillar center (FC), respectively. The right column (zoom × 16) corresponds to the enlarged images from the boxed areas. Scale bar represents 10 µm