Figure 1

NUP93, NUP107, and POM121 can potentially form NPC intermediates within pore-free islands. (a) Schematic representation of the positions of Nups (right half) and Nups subcomplexes (left half) in NPC. Dark grey boxes show Nups subcomplexes involved in interphase NPC assembly. Nups shown in blue are recognised by the mAb414 antibody, and Nups shown in yellow were tested in this study. (b) HeLa S3 cells were co-immunostained with antibodies against NUP93, NUP107, or POM121 as well as mAb414 (NPC). Rectangles 1 and 2 in the merged images indicate the enlarged positions 1 (pore-free island) and 2 (pore-rich region), respectively. Arrows and arrowheads indicate the position of pore-free islands (mAb414-free regions) and mAb414-independent Nup foci, respectively. Scale bar, 5 μm. (c) HeLa S3 cells were transfected with control siRNA (GL-2) or siRNA for Nups (NUP93, NUP107, or POM121), and cultured for 72 h. All images show the bottom surface of the NE. Arrows indicate the positions of pore-free islands. Scale bar, 5 μm. (d) Schematic illustration of the hypothesis regarding the disappearance of pore-free islands with cell cycle progression. Grey and red dots indicate old and newly-generated NPCs, respectively. In our hypothesis, pore-free islands disappeared through the establishment of de novo NPCs.