The C-terminal domain of Nup93 is essential for assembly of the structural backbone of nuclear pore complexes

Dimerization and direct membrane interaction of Nup53 contribute to nuclear pore complex assembly

Nuclear pore formation depends on membrane curvature. The membrane deforming activity of Nup53 is required for nuclear pore complex (NPC) assembly during interphase.

Nuclear pore complexes (NPCs) fuse the two membranes of the nuclear envelope (NE) to a pore, connecting cytoplasm and nucleoplasm and allowing exchange of macromolecules between these compartments. Most NPC proteins do not contain integral membrane domains and thus it is largely unclear how NPCs are embedded and anchored in the NE. Here, we show that the evolutionary conserved nuclear pore protein Nup53 binds independently of other proteins to membranes, a property that is crucial for NPC assembly and conserved between yeast and vertebrates. The vertebrate protein comprises two membrane binding sites, of which the C-terminal domain has membrane deforming capabilities, and is specifically required for de novo NPC assembly and insertion into the intact NE during interphase. Dimerization of Nup53 contributes to its membrane interaction and is crucial for its function in NPC assembly.

3D ultrastructure of the nuclear pore complex

Nuclear pore complexes (NPCs) perforate the double-layered nuclear envelope and form the main gateway for molecular exchange between nucleus and cytoplasm of the eukaryotic cell. Because NPCs are extraordinarily complex and large, thus challenging to investigate on a molecular level, they are still rather poorly understood, despite their pivotal role in cellular homeostasis. To decipher the NPC structure at high resolution, the prerequisite to fully understand its function, a tailored approach is necessary that feeds from complimentary data, obtained at largely different spatial resolutions. The problem is further complicated by the dynamic nature of the NPC, manifested in flexible regions and dynamic components. Here we summarize the current state of these structural efforts, describe the breakthroughs of recent years, point out the existing disputes in the field, and give an outlook of what we should expect to happen in the near future.