Postmitotic import of IBB, summary of kinetic results obtained in this study, and working model for the postmitotic assembly of the nuclear envelope and nuclear pores. (A) 2D time lapse of a mitotic HeLa cell expressing GFP-Sec61β and IBB-tomato acquired during nuclear envelope assembly (also see Video 7). Anaphase onset is at 0 s. At 660 s, imported IBB was clearly visualized next to the rim of the chromosome mass (arrows), at a time when assembly of the nuclear envelope is still incomplete as highlighted by the gap between the arrowheads. Key events were obtained by quantification of the Sec61β and IBB fluorescence signals. Bar, 10 µm. (B) Schematic summary of the relative kinetics of nuclear envelope formation and nucleoporin recruitment. The plots represent the fluorescence intensity associated with formation of the nuclear envelope (Sec61β, green; Fig. S1 B), recruitment of Nup133 (yellow; Fig. S1 C), recruitment of Nup62 (blue; Fig. S1 D), and import of IBB (red; Fig. S1 E). (C) Working model for the postmitotic assembly of the nuclear envelope and nuclear pores. ER is shown in light green; nuclear envelope (NE) is shown in dark green; yellow dot shows Nup107–160 complex; magenta dot shows remaining component of the nuclear pore; red square shows IBB; Chrom., chromosome mass.