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Spindle checkpoint maintenance requires Ame1 and Okp1.
Isabelle Pot1, James Knockleby, Victoria Aneliunas
1Department of Biochemistry & Molecular Biology and Centre for Molecular Medicine and Therapeutics, Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada.
Cell Cycle (Georgetown, Tex.)
|September 24, 2005
Summary
Ame1, a kinetochore protein, is crucial for maintaining cell cycle arrest during chromosome segregation. Its absence leads to defects and reduced cell viability, highlighting the importance of sustained checkpoint signaling.
Area of Science:
- Cell Biology
- Genetics
- Molecular Biology
Background:
- Kinetochore proteins ensure accurate chromosome segregation and checkpoint signaling.
- Ame1 is a key component of the COMA sub-complex in budding yeast.
Purpose of the Study:
- To characterize the Ame1 conditional mutant (ame1-4) and its role in chromosome segregation and cell cycle control.
- To investigate the contribution of Ame1 to checkpoint maintenance.
Main Methods:
- Isolation and characterization of the ame1-4 mutant.
- Monitoring chromosome segregation and cell cycle progression using markers like Bub3:VFP.
- Assessing cell viability at restrictive temperatures.
- Investigating the effect of OKP1 overexpression in the ame1-4 mutant.
Main Results:
- The ame1-4 mutant exhibits chromosome segregation defects and Mad2-dependent cell cycle delay.
- ame1-4 cells show significantly reduced viability compared to wild type and okp1-5 mutants.
- Cells lacking functional Ame1 initiate DNA duplication and budding with un-segregated chromosomes.
- Overexpressing OKP1 rescues Ame1 protein localization and restores a stable cell cycle arrest.
Conclusions:
- Ame1 and Okp1 are essential for a sustained checkpoint arrest when chromosomes are mis-segregated.
- Checkpoint response regulation involves both activation and maintenance signals.