FIGURE 7.

Nup153-Nup50 interaction is required for efficient nuclear import. A, frames from a live imaging movie showing import kinetics of RGG (green) in cells expressing mCherry (upper panels) or mCherry-Nup153(401–609) (lower panels) at 0, 12, 24, and 36 min after addition of dexamethasone (dex). Scale bar = 10 μm. B, quantification of raw fluorescence signal graphed as nuclear to total ratios (the mean for 25 control (blue squares) and 31 Nup153(401–609)-expressing (red triangles) cells), with error bars representing S.D. C, a working model is depicted in which two interfaces between the N-terminal region of Nup50 and Nup153, one mediated by importin α, aide in releasing the NLS cargo. Interaction between Nup153 and soluble factors CAS and Ran may create local concentrations that facilitate rapid capture of importin α for export.