The nucleoporin Nup153 is required for nuclear pore basket formation, nuclear pore complex anchoring and import of a subset of nuclear proteins

The nuclear pore complex (NPC) is a large proteinaceous structure through w hich bidirectional transport of macromolecules across the nuclear envelope (NE) takes place. Nup153 is a peripheral NPC component that has been implic ated in protein and RNP transport and in the interaction of NPCs with the n uclear lamina. Here, Nup153 is localized by immunogold electron microscopy to a position on the nuclear ring of the NPC. Nuclear reconstitution is use d to investigate the role of Nup153 in nucleocytoplasmic transport and NPC architecture. NPCs assembled in the absence of Nup153 lacked several nuclea r basket components, were unevenly distributed in the NE and, unlike wild-t ype NPCs, were mobile within the NE. Importin alpha/beta -mediated protein import into the nucleus was strongly reduced in the absence of Nup153, whil e transportin-mediated import was unaffected. This was due to a reduction i n import complex translocation rather than to defective receptor recycling. Our results therefore reveal functions for Nup153 in NPC assembly, in anch oring NPCs within the NE and in mediating specific nuclear import events.