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A role for the divergent actin gene, ACT2, in nuclear pore structure and function
1Department of Biological Sciences, Columbia University, New York, NY 10027, USA.
The EMBO Journal
|June 1, 1997
Summary
A yeast actin gene mutation (act2-1) disrupts nuclear pore complex structure and function, impacting nuclear import. This study reveals a novel nuclear role for Act2p in maintaining nuclear envelope integrity.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- The divergent actin gene ACT2 encodes Act2p, a protein with reported cytoskeletal functions.
- Previous studies suggest Act2p localization overlaps with conventional actin, implying a role in the cytoskeleton.
Purpose of the Study:
- To investigate the function of the yeast divergent actin gene ACT2.
- To elucidate the role of Act2p in nuclear pore complex (NPC) structure and nuclear import.
Main Methods:
- Isolation and characterization of a temperature-sensitive allele, act2-1.
- Immunofluorescence localization and cellular fractionation of epitope-tagged Act2p.
- Electron microscopy and immunoelectron microscopy to analyze NPC morphology.
- Synthetic lethality analysis and co-immunoprecipitation assays.
Main Results:
- The act2-1 mutation causes defects in NPC structure and nuclear import at restrictive temperatures.
- Electron microscopy revealed aberrant NPC morphology with densities containing XFXFG nucleoporins.
- act2-1 exhibited synthetic lethality with mutations in NUP1 and SRP1.
- Act2p and Srp1p were found to co-immunoprecipitate, indicating a protein complex.
Conclusions:
- Act2p plays a critical role in the structural integrity and function of nuclear pore complexes.
- Act2p is involved in nuclear import processes, independent of its potential cytoskeletal roles.
- The findings suggest a novel nuclear function for Act2p, interacting with nucleoporins and nuclear transport factors.