Transport receptor occupancy in nuclear pore complex mimics

Alessio Fragasso, Hendrik W. de Vries, John Andersson, Eli O. van der Sluis, Erik van der Giessen, Patrick R. Onck*, Cees Dekker*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

7 Citations (Scopus)
15 Downloads (Pure)


Nuclear pore complexes (NPCs) regulate all molecular transport between the nucleus and the cytoplasm in eukaryotic cells. Intrinsically disordered Phe-Gly nucleoporins (FG-Nups) line the central conduit of NPCs to impart a selective barrier where large proteins are excluded unless bound to a transport receptor (karyopherin; Kap). Here, we assess “Kap-centric” NPC models, which postulate that Kaps participate in establishing the selective barrier. We combine biomimetic nanopores, formed by tethering Nsp1 to the inner wall of a solid-state nanopore, with coarse-grained modeling to show that yeast Kap95 exhibits two populations in Nsp1-coated pores: one population that is transported across the pore in milliseconds, and a second population that is stably assembled within the FG mesh of the pore. Ionic current measurements show a conductance decrease for increasing Kap concentrations and noise data indicate an increase in rigidity of the FG-mesh. Modeling reveals an accumulation of Kap95 near the pore wall, yielding a conductance decrease. We find that Kaps only mildly affect the conformation of the Nsp1 mesh and that, even at high concentrations, Kaps only bind at most 8% of the FG-motifs in the nanopore, indicating that Kap95 occupancy is limited by steric constraints rather than by depletion of available FG-motifs. Our data provide an alternative explanation of the origin of bimodal NPC binding of Kaps, where a stable population of Kaps binds avidly to the NPC periphery, while fast transport proceeds via a central FG-rich channel through lower affinity interactions between Kaps and the cohesive domains of Nsp1. [Figure not available: see fulltext.]

Original languageEnglish
Pages (from-to)9689–9703
Number of pages15
JournalNano Research
Issue number11
Early online date1-Jul-2022
Publication statusPublished - Nov-2022


  • biomimetics
  • coarse-grained modeling
  • intrinsically disordered proteins
  • karyopherins
  • molecular dynamics
  • nanopores
  • nuclear pore complex
  • nuclear transport receptors

Cite this