Nuclear Pore Complexes: Architecture, Selective Transport and Plasticity

1. Scaffold architecture provides the channel framework

Structural work resolves the NPC as a composite assembly rather than a simple hole in the envelope. The cytoplasmic-face and linker-scaffold studies integrate structural information to identify how peripheral assemblies and connecting elements organize the pore. Different methods and species contribute to these models, so a composite architecture should not be described as one atomic image of an actively transporting human NPC. Its value is to identify component interfaces and constraints that can be tested through molecular perturbation and exchange assays. [2] [1]

Eibauer and colleagues examined NPC structure and gating in Xenopus oocytes, providing a distinct preparation-specific view of scaffold and channel organization. Comparison with newer models can reveal conserved organization and conformational flexibility, while differences in specimen and geometry remain important. A structural channel width does not by itself specify a passive-permeability coefficient or the transit time of a receptor-bound cargo. The dynamic barrier and cargo interactions occupy part of the same channel, so transport requires a functional account in addition to the scaffold dimensions. [9] [3] [8]

2. Pore composition and geometry are context dependent

Ori and colleagues examined cell-type-specific NPC stoichiometry using calibrated molecular-counting approaches. Their results caution against assuming invariant pore composition across human cell lines. The number and arrangement of structural copies can be assessed with suitable calibration, but they should not be converted into a universal count of identical machines in every nucleus. Composition can influence which molecular interactions are available, and its functional significance must be tested with corresponding transport or regulatory measurements. [11]

Morgan and colleagues used pan-expansion microscopy to examine NPC diameter distributions and surface-specific patterns in fixed cells. Hyperosmotic challenge and LINC perturbation affected aspects of those patterns, while a patient-derived neuronal comparison revealed a particular localization difference. These observations support environmental and cell-context plasticity. They do not alone establish a universal disease mechanism or quantify the functional consequence of each diameter. A distribution is informative because it preserves variation among pores rather than concealing it behind a single representative dimension. [7]

3. FG domains and transport factors create a dynamic barrier

FG-repeat nucleoporins provide interaction sites within the channel, but their collective organization depends on the native architectural context and the molecules present. Kozai and colleagues used high-speed AFM on isolated yeast NPCs with complementary approaches and described transport-factor-dependent organization of the barrier, including a mobile central cluster. Altering FG-domain content affected dynamics and transport. The study supports a dynamic barrier whose behavior depends on local occupancy and anchoring, rather than a permanently open cylinder or a static mass of interchangeable polymer. [8]

Reconstituted systems can dissect specific interactions but need not reproduce all native behavior. In the same study, DNA-origami nanopores with appropriately tethered FG domains and transport factors reproduced particular NPC-like features, whereas tested FG hydrogels behaved differently. This does not invalidate every hydrogel experiment; it identifies the property being modeled and the conditions needed for comparison. A native channel, a tethered mimic and a bulk FG assembly answer different mechanistic questions. Agreement on selective partitioning alone does not prove that their nanoscopic dynamics or geometry are identical. [8] [10]

A dynamic barrier can maintain selectivity without being structurally frozen. The high-speed-AFM work shows that molecular fluctuations and a mobile central organization can coexist with functional restriction. Thus, permeability should be viewed as an outcome of cargo encounters with a changing interaction environment, rather than requiring a permanently fixed aperture. Conversely, movement within the barrier does not prove unrestricted leakage. Functional passage and nanoscopic motion are different measurements that can be connected by changing defined barrier components and examining both readouts under the same condition. [8] [3]

Cargo retention after entry further complicates the relation between the pore and nuclear concentration. A transport assay that follows nuclear accumulation must account for how much cargo remains available for exchange. Import and export kinetics can be affected by the cargo’s binding or receptor state, while concentration ratios can also shift with accessible volume. The Ran experiments supply a route-specific molecular framework, and the YAP study illustrates how measuring import and export separately strengthens a mechanoregulation claim. A concentration endpoint becomes mechanistic when the relevant fluxes and available populations are resolved. [4] [17] [3]

Structural plasticity creates a similar need for joint measurements. Pan-expansion microscopy maps pore populations in different conditions, but the consequence of a given geometry may depend on the FG-domain and transport-factor state. A dilated channel with an altered barrier need not behave like a larger empty cylinder. Experiments relating diameter distributions to native barrier dynamics and defined-cargo exchange can determine which change matters for selectivity. This makes molecular occupancy an essential part of the geometry–function question, especially when comparing cell types with different pore composition. [7] [8] [11]

These developments also clarify what a successful pore mimic should reproduce. A model can be valuable for isolating one interface without matching every native component. Its validation should state whether it reproduces selective partitioning, cargo passage, scaffold geometry or barrier dynamics. The comparison of tethered DNA-origami pores and FG hydrogels demonstrates that agreement in one property does not ensure agreement in all the others. Used with that scope, reconstitution can identify mechanisms and then direct the next test in an intact cellular pore. [8] [10]

4. Passive exchange is graded for the examined cargoes

Timney and colleagues measured passive exchange of defined reporters in living yeast and found a size-dependent continuum rather than a sharp universal cutoff. Mohr and colleagues characterized barrier behavior in a different experimental preparation. These studies show that reporting only molecular mass omits cargo shape, interaction chemistry and assay context. A larger reporter may exchange slowly rather than be absolutely excluded, and a particular time window can make a slow process appear absent. Passive permeability should therefore be discussed as an experimentally measured exchange behavior, not a categorical rule based on one mass threshold. [3] [13]

A fluorescent nuclear-to-cytoplasmic concentration ratio is also insufficient to identify passive passage. Nuclear binding, active import, export and different accessible volumes can all contribute to steady-state distribution. To isolate permeability, the experiment needs defined reporters and controls for the relevant pathways or follows redistribution kinetics under the specified conditions. A change in concentration may be a useful phenotype while its mechanism remains unresolved. Distinguishing the phenotype from the inferred channel property is especially important when NPC geometry or composition changes in parallel. [3] [4] [7]

5. Receptor-mediated transport has directional chemistry

The experiments of Izaurralde and colleagues established the importance of the asymmetric Ran system for defined nuclear import and export pathways. Transport receptors interact with cargo and NPC constituents, while the spatially organized Ran cycle supports directionality. The NPC consequently provides an interaction environment rather than a motor that pushes every cargo through in the same way. This framework should not be generalized to every RNA-export route, and it does not mean that each physical passage requires a separate ATP-consuming step within the channel. [4] [5]

mRNA export includes remodeling at the cytoplasmic face, exemplified by the Dbp5 nucleotide cycle regulated by Nup159 and Gle1. The primary study connects molecular regulation to the handling of a specific ribonucleoprotein substrate. Its mechanism differs from a simple Ran-dependent import/export analogy. A current pore review should therefore distinguish the transit interface from the cargo-preparation and remodeling reactions associated with it. Failure of an RNA-export factor can change nuclear retention without establishing that the scaffold diameter or the passive barrier has been altered. [5] [4]

6. Cargo interaction can matter as much as size

Dickson and colleagues dissected HIV-capsid interactions with FG-nucleoporin assemblies and identified engagement consistent with karyopherin mimicry. Their reconstituted experiments showed that a specialized large cargo can exploit specific interactions with the barrier. This adds a molecular explanation beyond a size-only description. It is not a complete measurement of intact NPC crossing in every living human cell, and viral capsids should not be used as a generic model for all large cellular cargoes. The preparation and molecular interaction tested remain central to the result. [10]

The barrier-remodeling findings of Kozai and colleagues similarly connect transport-factor occupancy with channel behavior. Cargo passage is therefore influenced by the environment into which it enters and the interactions it can make, as well as its dimensions. This supplies a route to test selectivity experimentally: change a defined cargo interface or transport-factor condition while following passage and barrier dynamics. A result that changes partitioning in a bulk assembly should be distinguished from altered passage through a correctly anchored mimic or a native pore. [8] [10] [3]

7. Assembly must coordinate membrane topology and function

Otsuka and colleagues resolved interphase NPC assembly intermediates consistent with an inside-out extrusion through the existing nuclear envelope. This pathway must establish a new channel without broadly disrupting compartmentalization. It differs from pore formation during postmitotic envelope reconstruction. Structural intermediates help infer the order of membrane remodeling, but observing an intermediate does not prove that all components have reached a transport-competent final configuration. Assembly studies gain explanatory strength by pairing recruitment and membrane morphology with subsequent exchange measurements. [14] [3]

Postmitotic boundary sealing illustrates the related distinction between membrane coverage and a functional barrier. The ESCRT and LEM2 studies identified mechanisms restoring compartmentalization around daughter chromatin. Those experiments address residual membrane openings and spindle-associated remodeling rather than the entire assembly sequence of a mature NPC. Keeping the mechanisms separate prevents a transport defect after mitosis from being attributed automatically to pore structure when incomplete membrane sealing could provide another explanation. The relevant observation is where exchange occurs and whether the enclosing membrane is intact. [15] [16] [14]

8. Current studies link NPCs to deformation and fluid flow

Elosegui-Artola and colleagues showed force-dependent YAP nuclear entry in defined cell systems and connected it to altered import behavior. The experiment demonstrates regulation of a particular cargo under mechanical loading. Morgan and colleagues subsequently mapped structural plasticity with pan-expansion microscopy, offering complementary evidence about pore geometry. These observations motivate joint structure–function experiments, but they do not prove that every cargo response under force is explained solely by dilation or that geometry alone is sufficient to predict its kinetics. [17] [7]

Hoffmann and colleagues examined pressure-dependent fluid flow across NPCs in Dictyostelium during osmotic adaptation, relating flow to the dilation state and testing pore blockage. This mode differs from canonical diffusion and receptor-mediated exchange because a pressure difference contributes to the driving force. The result broadens the functional account of an NPC beyond discrete molecular cargo passage. Its implications for mammalian volume regulation require matching the relevant physical conditions rather than treating the slime-mold observation as a direct measurement of every human pore. [6] [18]

9. Pore maintenance and disease evidence require specific models

D’Angelo and colleagues linked deterioration of long-lived NPC components to loss of nuclear integrity in defined postmitotic systems. The study addresses maintenance over time and differs from acute membrane rupture during cell migration. It does not establish that every NPC component has the same lifetime or that all ordinary human aging is caused by pore deterioration. A disease-oriented interpretation should identify which component, cell state and functional assay support the claim before extending it to another lineage or disorder. [12] [19]

10. An integrated contemporary model

The NPC is best described as a structured and dynamic selective interface. Scaffold geometry constrains the channel, FG domains and transport factors organize its interaction environment, and cargo-specific chemical cycles establish directionality. Current primary studies show that composition and dilation can vary and that pressure-dependent flow supplies another mode of exchange. The next step is to connect architecture, occupancy and functional transport in matched biological systems, so that a structural change can be assigned a specific consequence rather than assumed to alter every pathway equally. [1] [8] [4] [5] [7] [6]

References

1. [1] Stefan Petrovic, Dipanjan Samanta, Thibaud Perriches et al. (2022). Architecture of the linker-scaffold in the nuclear pore. Science. 10.1126/science.abm9798
   Evidence and source scope

   Source type: primary. Access: Selected indexed primary main text (opening8000chars; not complete article), plus metadata..

   Linker/scaffold structural integration and flexible ring-spoke models; model architecture not universal transport threshold.

   No indexed notice in retrieved result is not a guarantee of no correction/retraction. New records lacked complete Scite notice check after monthly quota.

2. [2] Christopher J. Bley, Si Nie, George W. Mobbs et al. (2022). Architecture of the cytoplasmic face of the nuclear pore. Science. 10.1126/science.abm9129
   Evidence and source scope

   Source type: primary. Access: Selected indexed primary main text (opening8000chars; not complete article), plus metadata..

   Composite human/fungal cytoplasmic-face architecture and approximate composition; not one atomic image of a functioning pore.

   No indexed notice in retrieved result is not a guarantee of no correction/retraction. New records lacked complete Scite notice check after monthly quota.

3. [3] Benjamin L. Timney, Barak Raveh, Roxana Mironska et al. (2016). Simple rules for passive diffusion through the nuclear pore complex. Journal of Cell Biology. 10.1083/jcb.201601004
   Evidence and source scope

   Source type: primary. Access: Primary abstract and bibliographic metadata; complete body unavailable through connector..

   Gradual size-dependent passive NPC reporter exchange in yeast; not a hard universal mass cutoff or whole-nucleoplasm diffusion law.

   No indexed notice in retrieved result is not a guarantee of no correction/retraction. New records lacked complete Scite notice check after monthly quota.

4. [4] Elisa Izaurralde, Ulrike Kutay, Cayetano von Kobbe et al. (1997). The asymmetric distribution of the constituents of the Ran system is essential for transport into and out of the nucleus. The EMBO Journal. 10.1093/emboj/16.21.6535
   Evidence and source scope

   Source type: primary. Access: Selected indexed primary main text (opening8000chars; not complete article), plus metadata..

   Ran-system asymmetry regulates particular import/export reporters; not all cargo uses the same energy mechanism.

   No indexed notice in retrieved result is not a guarantee of no correction/retraction. New records lacked complete Scite notice check after monthly quota.

5. [5] Kristen N. Noble, Elizabeth Tran, Abel R. Alcázar-Román et al. (2011). The Dbp5 cycle at the nuclear pore complex during mRNA export II: nucleotide cycling and mRNP remodeling by Dbp5 are controlled by Nup159 and Gle1. Genes & Development. 10.1101/gad.2040611
   Evidence and source scope

   Source type: primary. Access: Selected indexed primary main text (opening8000chars; not complete article), plus metadata..

   Nup159/Gle1-IP6 regulation of Dbp5 nucleotide/remodeling cycles; distinct from general Ran-mediated traffic.

   No indexed notice in retrieved result is not a guarantee of no correction/retraction. New records lacked complete Scite notice check after monthly quota.

6. [6] Patrick C. Hoffmann, Hyuntae Kim, Aleksandra Obarska-Kosińska et al. (2024). Nuclear pore permeability and fluid flow are modulated by its dilation state. Molecular Cell. 10.1016/j.molcel.2024.11.038
   Evidence and source scope

   Source type: primary. Access: Consensus fetched primary record and search-returned primary abstract; full Results inaccessible. Online 2024; issue year should not replace online publication date..

   Dictyostelium osmotic adaptation, dilation-dependent pressure-driven nucleocytosolic fluid flow and viral blockage; not identical to diffusion or receptor-driven transport.

   No independent experimental replication or raw-data reanalysis. Source interpretation confined to the stated access depth.

7. [7] Kimberly J. Morgan, Emma Carley, Alyssa N. Coyne, Jeffrey D. Rothstein, C. Patrick Lusk, Megan C. King (2025). Visualizing nuclear pore complex plasticity with pan-expansion microscopy. Journal of Cell Biology. 10.1083/jcb.202409120
   Evidence and source scope

   Source type: primary. Access: Fetched primary abstract and publication record; full Methods and Results not yet appraised..

   Expanded fixed-cell NPC diameter distributions, nuclear-surface bias, hyperosmotic constriction and LINC perturbation; one patient-derived neuronal comparison does not establish all ALS.

   No independent experimental replication or raw-data reanalysis. Source interpretation confined to the stated access depth.

8. [8] Toshiya Kozai, Javier Fernandez-Martinez, Larisa E. Kapinos et al. (2025). Karyopherins remodel the dynamic organization of the nuclear pore complex transport barrier. Nature Cell Biology. 10.1038/s41556-025-01812-9
   Evidence and source scope

   Source type: primary. Access: Publisher primary Abstract, opening Results on isolated yeast NPCs, selected DNA-origami Results and Discussion read; entire Methods and supplements not appraised..

   High-speed AFM of isolated yeast NPCs and orthogonal approaches; transport-factor-dependent FG organization, mobile central cluster, altered FG mutants, and contrast with hydrogels.

   No independent experimental replication or raw-data reanalysis. Source interpretation confined to the stated access depth.

9. [9] Matthias Eibauer, Mauro Pellanda, Yagmur Turgay et al. (2015). Structure and gating of the nuclear pore complex. Nature Communications. 10.1038/ncomms8532
   Evidence and source scope

   Source type: primary. Access: Selected indexed primary main text (opening8000chars; not complete article), plus metadata..

   Xenopus oocyte NPC cryo-tomographic scaffold/channel structure; not direct universal transport kinetics.

   No indexed notice in retrieved result is not a guarantee of no correction/retraction. New records lacked complete Scite notice check after monthly quota.

10. [10] Claire F. Dickson, Sophie Hertel, Andrew Tuckwell et al. (2024). The HIV capsid mimics karyopherin engagement of FG-nucleoporins. Nature. 10.1038/s41586-023-06969-7
    Evidence and source scope

    Source type: primary. Access: Fetched Consensus primary abstract/record, cross-checked with SciSpace where available; complete body not appraised..

    The Dickson et al. (2024) used an in-vitro dissection of the nuclear barrier and identified a capsid pocket engaging FG motifs from several nucleoporins. Capsids penetrated tested FG condensates, supporting a karyopherin-mimicry interpretation for a large viral cargo. This illustrates why interaction chemistry matters alongside size. Reconstituted-condensate entry is not identical to passage kinetics through an intact, mechanically changing NPC in a living human cell. Dickson et al. (2024) .

    No indexed notice in retrieved result is not a guarantee of no correction/retraction. New records lacked complete Scite notice check after monthly quota.

11. [11] Alessandro Ori‬‬, Niccolò Banterle, Murat Iskar et al. (2013). Cell type‐specific nuclear pores: a case in point for context‐dependent stoichiometry of molecular machines. Molecular Systems Biology. 10.1038/msb.2013.4
    Evidence and source scope

    Source type: primary. Access: Selected indexed primary main text (opening8000chars; not complete article), plus metadata..

    NPC stoichiometry comparisons across human cell lines and calibrated counting; no invariant universal composition.

    No indexed notice in retrieved result is not a guarantee of no correction/retraction. New records lacked complete Scite notice check after monthly quota.

12. [12] Maximiliano A. D’Angelo, Marcela Raı́ces, Siler H. Panowski et al. (2009). Age-Dependent Deterioration of Nuclear Pore Complexes Causes a Loss of Nuclear Integrity in Postmitotic Cells. Cell. 10.1016/j.cell.2008.11.037
    Evidence and source scope

    Source type: primary. Access: Primary abstract and bibliographic metadata; complete body unavailable through connector..

    Long-lived scaffold components and age-associated permeability loss in defined postmitotic models; not all human ageing or every NPC component.

    No indexed notice in retrieved result is not a guarantee of no correction/retraction. New records lacked complete Scite notice check after monthly quota.

13. [13] Dagmar Mohr, Steffen Frey, Torsten Fischer et al. (2009). Characterisation of the passive permeability barrier of nuclear pore complexes. The EMBO Journal. 10.1038/emboj.2009.200
    Evidence and source scope

    Source type: primary. Access: Primary abstract and bibliographic metadata; complete body unavailable through connector..

    Probe passage in permeabilized nuclei and barrier perturbations; distinct from living-yeast passive exchange.

    No indexed notice in retrieved result is not a guarantee of no correction/retraction. New records lacked complete Scite notice check after monthly quota.

14. [14] Shotaro Otsuka, Khanh Huy Bui, Martin Schorb et al. (2016). Nuclear pore assembly proceeds by an inside-out extrusion of the nuclear envelope. eLife. 10.7554/eLife.19071
    Evidence and source scope

    Source type: primary. Access: Selected indexed primary main text (opening8000chars; not complete article), plus metadata..

    Correlative main-text interphase NPC membrane intermediates; not a full mitotic assembly account.

    No indexed notice in retrieved result is not a guarantee of no correction/retraction. New records lacked complete Scite notice check after monthly quota.

15. [15] Yolanda Olmos, Lorna Hodgson, Judith Mantell, Paul Verkade, Jeremy G. Carlton (2015). ESCRT-III controls nuclear envelope reformation. Nature. 10.1038/nature14503
    Evidence and source scope

    Source type: primary. Access: Fetched primary abstract and identity; full Methods not accessible..

    CHMP2A/CHMP4B/UFD1-dependent postmitotic envelope sealing and compartmentalization in human cells, not all envelope-repair routes.

    No independent experimental replication or raw-data reanalysis. Source interpretation confined to the stated access depth.

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    Evidence and source scope

    Source type: primary. Access: Fetched primary abstract and identity plus selected primary Results excerpts; complete Methods/supplements not appraised..

    LEM2 chromatin/microtubule targeting and CHMP7 activation in postmitotic reformation; O-ring is mechanistic model, not every membrane-less-body mechanism.

    No independent experimental replication or raw-data reanalysis. Source interpretation confined to the stated access depth.

17. [17] Alberto Elosegui-Artola, Ion Andreu, Amy E. M. Beedle et al. (2017). Force Triggers YAP Nuclear Entry by Regulating Transport across Nuclear Pores. Cell. 10.1016/j.cell.2017.10.008
    Evidence and source scope

    Source type: primary. Access: Publisher primary selected Results on force application and import/export plus AFM Methods excerpt read; complete body and supplements not appraised..

    Force-dependent YAP entry in defined fibroblast/MCF10A systems, nuclear deformation and import-rate assays; not all cargo or universal pore-mechanics explanation.

    No independent experimental replication or raw-data reanalysis. Source interpretation confined to the stated access depth.

18. [18] Abin Biswas, Omar Muñoz, Kyoohyun Kim et al. (2025). Conserved nucleocytoplasmic density homeostasis drives cellular organization across eukaryotes. Nature Communications. 10.1038/s41467-025-62605-0
    Evidence and source scope

    Source type: primary. Access: Fetched primary abstract and publisher Results excerpts on Xenopus assembly and density model; Crossmark publication date and author metadata checked. Complete body and supplements not appraised..

    Nuclear/cytoplasmic density differences and pressure-balance model constrained by transport, chromatin and embryo observations. Erroneous2023 provider year corrected to publisher15August2025.

    No independent experimental replication or raw-data reanalysis. Source interpretation confined to the stated access depth.

19. [19] Céline Denais, Rachel M. Gilbert, Philipp Isermann et al. (2016). Nuclear envelope rupture and repair during cancer cell migration. Science. 10.1126/science.aad7297
    Evidence and source scope

    Source type: primary. Access: Primary author-manuscript main Abstract/Results pages1–4 and Figures1/2/4; supplementary Methods and raw data not reanalysed..

    NLS-reporter rupture, defined in-vitro and mouse-dermis models, deformation-associated damage foci and ESCRT-III-dependent resealing independently match primary main Results/Figures. Mixed-topic Scite opening excluded.

    No indexed notice in retrieved result is not a guarantee of no correction/retraction. New records lacked complete Scite notice check after monthly quota.

Evidence scope

This review integrates published primary research with a foundational methods review where needed. Source access ranges from primary abstracts to the selected main Results and Methods identified in each reference record. It is a scholarly synthesis rather than an independent reanalysis of experimental data. Conclusions retain the biological system, measurement scale and model assumptions of the cited studies.