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Nuclear pore complexes exceeding eightfold rotational symmetry.
Jenny E Hinshaw1, Ronald A Milligan
1Laboratory of Cell Biochemistry and Biology, NIDDK, National Institutes of Health, 8 Center Drive, Building 8, Room 419, Bethesda, MD 20892, USA. jennyh@helix.nih.gov
Journal of Structural Biology
|March 22, 2003
Summary
Unusual nuclear pore complexes (NPCs) with 9- and 10-fold symmetry share immutable spoke substructures with 8-fold NPCs. Identical annular subunit spacing suggests these connections are key to NPC assembly and stability.
Area of Science:
- Cell biology
- Structural biology
- Biophysics
Background:
- Nuclear pore complexes (NPCs) regulate transport between the nucleus and cytoplasm.
- NPCs typically exhibit eight-fold rotational symmetry.
- Rare 9- and 10-fold symmetric NPCs have been observed in Xenopus oocyte macronuclei.
Purpose of the Study:
- To investigate the structural basis of 9- and 10-fold symmetric NPCs.
- To compare the structural components of varied NPC symmetries.
- To elucidate the role of subunit interactions in NPC assembly and stability.
Main Methods:
- Negative stain electron microscopy
- Image analysis
- 3D reconstruction
- Comparative structural analysis
Main Results:
- The spoke substructure is conserved across 8-, 9-, and 10-fold symmetric NPCs, indicating it's an immutable component.
- The spacing between adjacent annular subunits is identical in all observed symmetries.
- Inter-spoke distances decrease at higher radii in 9- and 10-fold NPCs compared to 8-fold NPCs.
Conclusions:
- Annular subunit interactions are critical for NPC assembly and overall structural integrity.
- The flexibility of ring subunits and radial arms accommodates variations in spoke number.
- NPC assembly is likely driven by strong interactions between adjacent annular subunits.