FIG. 3.

Sequence specific nuclear import of Rex in digitonin-permeabilized HeLa cells. In vitro import assays were performed using fusions of the wild-type Rex NLS (a and b), the 1 + 2 mutant variant of the Rex NLS (c and d) or the wild-type T antigen NLS (e and f) to the carboxy terminus of GST as substrates. Import factors were supplied using HeLa cell cytosol and reactions were run for 30 min in the presence of an energy regenerating system. Samples were analyzed by indirect immunofluorescence using a GST-specific monoclonal antibody followed by a Texas red-conjugated secondary antibody and epifluorescence (a, c, and e). The corresponding phase-contrast analyses are also shown (b, d, and f).