(A) Confocal microscopy images of nuclei assembled for 120 min in mock depleted, Nup50 depleted (∆Nup50), and Nup50 depleted Xenopus egg extracts supplemented with recombinant wild-type Nup50 or different mutants. Nuclei were fixed in 4% PFA and 0.5 % glutaraldehyde, stained for NPCs (mAB414) and the chromatin (DAPI). Scale bar: 10 µm. (B) Average percentage of mAB414 positive nuclei for 100 randomly chosen chromatin substrates in each of at least three independent experiments shown in (A). Data points from the individual experiments are indicated. 