Related Experiment Video
Updated: Aug 17, 2026

Characterizing DNA Repair Processes at Transient and Long-lasting Double-strand DNA Breaks by Immunofluorescence Microscopy
Published on: June 8, 2018
Sister chromatid separation and chromosome re-duplication are regulated by different mechanisms in response to
G Alexandru1, W Zachariae, A Schleiffer
1Research Institute of Molecular Pathology, Dr. Bohr-Gasse 7, A-1030 Vienna, Austria.
Abstract:
In yeast, anaphase entry depends on Pds1 proteolysis, while chromosome re-duplication in the subsequent S-phase involves degradation of mitotic cyclins such as Clb2. Sequential proteolysis of Pds1 and mitotic cyclins is mediated by the anaphase-promoting complex (APC). Lagging chromosomes or spindle damage are detected by surveillance mechanisms (checkpoints) which block anaphase onset, cytokinesis and DNA re-replication. Until now, the MAD and BUB genes implicated in this regulation were thought to function in a single pathway that blocks APC activity. We show that spindle damage blocks sister chromatid separation solely by inhibiting APCCdc20-dependent Pds1 proteolysis and that this process requires Mad2. Blocking APCCdh1-mediated Clb2 proteolysis and chromosome re-duplication does not require Mad2 but a different protein, Bub2. Our data imply that Mad1, Mad2, Mad3 and Bub1 regulate APCCdc20, whereas Bub2 regulates APCCdh1.
Related Concept Videos
Homologous Recombination
Cohesins
Cohesin complexes in Meiotic Division
Meiosis involves two distinct rounds of chromosomal segregation and cell divisions— Meiosis I followed by Meiosis II – producing four daughter cells. Meiosis I includes the separation of homologous...
Separation of Sister Chromatids
At the onset of anaphase, separase, a proteolytic enzyme, is...
The Spindle Assembly Checkpoint
Many proteins function together to control the spindle assembly checkpoint. Mutations affecting these proteins may allow cells to proceed into anaphase prematurely, resulting in the...
Separation of Sister Chromatids
At the onset of anaphase, separase, a proteolytic enzyme, is...
The Spindle Assembly Checkpoint
Many proteins function together to control the spindle assembly checkpoint. Mutations affecting these proteins may allow cells to proceed into anaphase prematurely, resulting in the...

