Schematic representation of nuclear pore complex (NPC) architecture, subcomplex composition, and localization within the NPC. (a) Xenopus oocyte nuclei have millions of closely packed NPCs and a cross-section along an embedded nuclear envelope from these nuclei offer side views of NPC architecture that can be visualised by transmission electron microscopy. Shown are a selected NPC in side view (left) and a schematic diagram of the main structural components of NPCs (right). Scale bar, 100 nm. (b) Linear dimensions of the central framework of the human NPC. Numbers are according to [10]. (c) Nucleoporins can be classified in different subgroups depending on their structural motifs and their localization: transmembrane proteins (white), scaffold nucleoporins (light grey), nucleoporins of the cytoplasmic filaments (gradient), central channel nucleoporins (middle grey), and nuclear basket nucleoporins (dark grey). Nup153 has two anchoring domains at the nuclear basket, the N terminus close to the nuclear ring and a zinc-finger domain at the distal ring of the nuclear basket. Nup88 is also found in the proximity of the nuclear ring and Nup50 is a mobile nucleoporin associated with the nuclear basket.