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#NPC

2 public questions tagged with this topic.

The nuclear pore complex (NPC) primarily consists of:

Nuclear pore complexes are massive one hundred ten to one hundred twenty megadalton assemblies spanning two lipid bilayers with eightfold rotational symmetry, comprised of about thirty distinct proteins called nucleoporins organized into scaffold and barrier layers. Y-complex Nup107-Nup160 forms outer rings, Nup93-Nup205 inner ring, and intrinsically disordered FG-repeat nucleoporins such as Nup62 complex, Nup98, Nup214 line central channel forming selective hydrogel that blocks nonspecific diffusion above forty kDa while allowing receptor-mediated transport. Importin beta family receptors bind nuclear localization signals and traverse FG mesh by transient hydrophobic interactions, exportins bind nuclear export signals in Ran-GTP dependent manner. Cytoplasmic filaments contain Nup358, nuclear basket contains Tpr. Actin filaments, spectrin network and dynein motors are cytoplasmic cytoskeletal components not part of pore scaffold. Knockdown of scaffold nucleoporins causes nuclear export defects and developmental arrest, while FG nucleoporin mutations linked to leukemia illustrate essential role in nucleocytoplasmic exchange maintaining compartment identity. Integration with cell cycle kinases, calcium signaling and mechanical cues ensures coordinated remodeling during growth, migration and differentiation.

Ref: Rout & Aitchison Annu Rev Biochem; NPC 30 nucleoporins FG barrier selective transport.

What is the function of the nuclear pore complex (NPC)?

Barrier between genome and cytoplasm is perforated by nuclear pore complexes large supramolecular structures of approximately 125 megadaltons composed of about 30 distinct nucleoporins present in multiple copies arranged with eightfold rotational symmetry spanning double nuclear membranes. Outer scaffold comprises Y-shaped Nup107-160 subcomplex forming two concentric rings, inner ring composed of Nup205, Nup188, Nup155 anchoring central channel filled with disordered FG repeats rich in phenylalanine-glycine motifs that form selective phase limiting diffusion. Molecules smaller than 40 kilodalton diffuse passively, larger cargo requires transport receptors karyopherin family interacting via hydrophobic patches with FG repeats. Import receptors importin alpha/beta recognize basic nuclear localization signals with clusters of lysine and arginine, while export receptor CRM1/XPO1 binds leucine-rich nuclear export signals. Ran-GTP gradient provides directionality dissociating import and promoting export complexes. NPC therefore gates transcription factors, histones, ribosomal subunits, and messenger ribonucleoproteins, controlling gene expression, DNA repair factor availability, and development, with dysfunction linked to cancer and viral infections.

Ref: Hurt & Beck, Cell 2015, Nuclear Pore Architecture. Alberts 7th ed., Chapter 12, NPC Function.