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The small GTPase Ran defines nuclear pore complex asymmetry
Jenny Sachweh1, Mandy Börmel2, Sven Klumpe3
1Department of Molecular Sociology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany.
Cell
|August 19, 2025
Summary
Nuclear pore complexes (NPCs) are key to nucleocytoplasmic exchange. This study reveals how NPCs achieve asymmetric structure from a symmetric scaffold, controlled by the Ran GTPase, suggesting a self-regulatory transport system.
Area of Science:
- Cell Biology
- Structural Biology
- Molecular Biology
Background:
- Nuclear pore complexes (NPCs) regulate transport between the nucleus and cytoplasm.
- NPCs exhibit asymmetric structures crucial for directional transport.
- The assembly of these asymmetric structures onto a symmetric scaffold remained poorly understood.
Purpose of the Study:
- To elucidate the mechanism of asymmetric nuclear pore complex assembly.
- To investigate the role of the Ran GTPase in NPC structure and function.
- To understand the self-regulatory nature of the nuclear transport system.
Main Methods:
- Cryo-electron tomography
- Subtomogram averaging
- Template matching
- Live imaging in budding yeast and Drosophila
- Genetic induction of ectopic nuclear pores
Main Results:
- Ectopic nuclear pores formed outside the nuclear envelope were found to be symmetric.
- The peripheral structure of NPCs is influenced by the nucleotide state of the Ran GTPase.
- Evidence suggests a unified mechanism controls both NPC transport and composition.
Conclusions:
- The nuclear transport system is self-regulatory.
- The same molecular mechanism governs both nucleocytoplasmic transport and the composition of the transport channel.
- Ran GTPase plays a critical role in establishing NPC asymmetry.
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