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The yeast nuclear pore complex functionally interacts with components of the spindle assembly checkpoint.
Tatiana Iouk1, Oliver Kerscher, Robert J Scott
1Department of Cell Biology, University of Alberta, Edmonton, Alberta, T6G 2H7 Canada.
The Journal of Cell Biology
|December 11, 2002
Summary
The nuclear pore complex (NPC) physically links to the spindle checkpoint machinery. Mad1p and Mad2p proteins at the NPC are released upon checkpoint activation, influencing nuclear transport.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- The spindle checkpoint ensures accurate chromosome segregation during cell division.
- Proteins Mad1p and Mad2p are crucial for spindle checkpoint function.
- The nuclear pore complex (NPC) regulates transport between the nucleus and cytoplasm.
Purpose of the Study:
- To investigate the physical and functional relationship between the NPC and spindle checkpoint proteins Mad1p and Mad2p.
- To elucidate the role of NPC-associated proteins in spindle checkpoint activation and nuclear transport.
Main Methods:
- Immunofluorescence microscopy to localize proteins.
- Co-immunoprecipitation to study protein interactions.
- Genetic analysis of double mutants in Saccharomyces cerevisiae.
- Analysis of protein phosphorylation and release from the NPC.
Main Results:
- Mad1p and Mad2p proteins are predominantly localized at the NPC throughout the cell cycle.
- These proteins associate with a nucleoporin subcomplex including Nup53p, Nup170p, and Nup157p.
- Spindle checkpoint activation leads to Mad2p release from the NPC and Mad1p hyperphosphorylation.
- Mad1p association with the NPC is not passive and affects nuclear transport.
Conclusions:
- A physical and functional link exists between the NPC and spindle checkpoint machinery.
- Mad1p sequesters Mad2p at the NPC until checkpoint activation, facilitating its release to kinetochores.
- The NPC plays an active role in regulating spindle checkpoint function and nuclear transport.