Figure 1.

λ Phage DNA is concentrated in reconstituted nuclei, but responds differently than NLS-protein transport substrate to inhibitors of protein import. Each panel shows a single nucleus imaged by scanning confocal microscopy, with fluorescent molecules as marked: protein [human serum albumin (HSA)-NLS or BSA-NLS] in column 1, DNA in column 2, and 167-kDa dextran in column 3. Each row in columns 2 and 3 show the same nuclei in two color channels. (A–C) Both DNA and protein are accumulated in intact nuclei. (D–I) Protein import is sensitive to ATP depletion and cold incubation, whereas DNA uptake is not. (J–L) Wheat germ agglutinin blocks both protein and DNA accumulation. (M–O) the fluorescent labeling reagent (see Materials and Methods) is not specifically accumulated in the nucleus: (M) differential interference contrast image; (N and O) fluorescence of Cy3 and dextran, respectively. (Scale bars, 5 μm.)