Nucleocytoplasmic Transport Mechanisms in Eukaryotic Systems

Nucleocytoplasmic transport is a fundamental process that regulates the bidirectional movement of macromolecules between the nuclear and cytoplasmic compartments. Central to this system are nuclear pore complexes (NPCs), large protein assemblies that span the nuclear envelope and provide selective channels for transport. Transport receptors of the karyopherin family—including importins for nuclear entry and exportins for nuclear exit—recognise specific targeting signals on cargo molecules. Directionality is conferred by the Ran GTPase cycle, which alternates between GTP- and GDP-bound states in distinct subcellular locales, thereby driving cargo release or capture. Beyond simple transit, transport components contribute to chromatin organisation, gene expression control and quality control of nascent proteins. Dysregulation of nucleocytoplasmic transport underlies numerous pathologies, from viral hijacking of the transport machinery to aberrant localisation of tumour suppressors and oncoproteins. Advances in high-resolution structural biology, combined with proteomic and biophysical approaches, have begun to reveal the dynamic interactions, regulatory post-translational modifications and feedback loops that fine-tune transport rates in response to cellular stress, developmental cues and disease states. This mechanistic understanding not only illuminates basic cell-biological principles but also informs the development of transport-modulating therapeutics in cancer, neurodegeneration and infectious disease.

Research from Nature Portfolio

Recent studies have demonstrated that certain importin family members engage nascent polypeptides co-translationally at the ribosome, linking early cargo folding to nuclear import. By systematically profiling importin–ribosome interactions, researchers identified importins that bind aggregation-prone protein families, including ribosomal proteins and chromatin regulators, as they emerge from the exit tunnel. This co-translational chaperoning mechanism operates alongside classical ribosome-associated chaperones, preventing misfolding and premature aggregation in the cytosol. Consequently, the nuclear import system is now seen as an integrated quality-control network that ensures proteostasis from synthesis to nuclear delivery.

Nucleocytoplasmic Transport Mechanisms in Eukaryotic Systems publication trend

The graph below shows the total number of articles in nucleocytoplasmic transport mechanisms in eukaryotic systems across all publications each year (not limited to Nature Index journals).

Technical terms

Nuclear pore complex (NPC): Multi-protein assembly forming a selective gateway through the nuclear envelope.

Karyopherin: Transport receptor family that mediates import (importins) or export (exportins) of cargoes.

Ran GTPase cycle: Molecular switch driven by Ran-GTP and Ran-GDP gradients that determines transport directionality.

Nuclear localisation signal (NLS): Short amino-acid motif that directs cargo recognition by importins for nuclear entry.

Nuclear export signal (NES): Short leucine-rich motif recognised by exportins to facilitate nuclear exit of proteins or RNAs.

Proteostasis: Cellular network ensuring correct folding, maintenance and degradation of proteins.

References

1. Nuclear transport proteins: structure, function and disease relevance. Signal Transduction and Targeted Therapy (2023).
2. Co-translational binding of importins to nascent proteins. Nature Communications (2023).
3. Altered RNA export by SF3B1 mutants confers sensitivity to nuclear export inhibition. Leukemia (2024).
4. Types of nuclear localization signals and mechanisms of protein import into the nucleus. Cell Communication and Signaling (2021).
5. Six Classes of Nuclear Localization Signals Specific to Different Binding Grooves of Importin α*. Journal of Biological Chemistry (2008).