Fig. 6. Nuclear import complexes form and dock on the NE of the digitonin-permeabilized HeLa cells following the addition of either wild-type (A) or P446L mutant importin-ß (C) in the presence of the fluorescent IBB-nucleoplasmin fusion protein. Upon addition of the import mixture (the fluorescent IBB-nucleoplasmin fusion protein, Ran, NTF2, RanGAP, RanBP1 and energy supply) and the wild-type importin-ß, nuclear import complexes form and enter the nuclei (B). However, when P446L mutant importin-ß is added along with the import mixture, import complexes do not form and the HeLa cell nuclei are not highlighted by fluorescent signal (D). Bar, 10 µm.