FIG. 2.

Vpx is imported into the nucleus by a signal-mediated pathway. (A) Photomicrographs of transfected HeLa cells that express the indicated fusion constructs. HeLa cells were transfected with plasmids that encode GFP-Vpx, Vpx1-40, Vpx65-75, the HIV-1 Rev NLS, and the SV40 NLS or the control protein, GFP. At 12 h after transfection, cells were treated (+) with digitonin at 55 μg/ml or were not treated (−) with digitonin and then fixed in 3% paraformaldehyde. The fusion proteins were directly visualized by epifluorescence microscopy. (B) Vpx nuclear import is sensitive to wheat germ agglutinin. Vpx, Rev NLS, and SV40 NLS expression plasmids were transfected into Cos-7 cells and observed for nuclear import in the presence of 0.5 mg of WGA/ml (+WGA) or in the absence of WGA (−WGA) All samples were analyzed by fluorescence microscopy as described in the legend for Fig. 1. DAPI, 4′,6′-diamidino-2-phenylindole.