Model Showing the Functions of BUB1 and BUBR1 in the Mitotic Spindle Biology Diagrams Bernard, P., Hardwick, K. & Javerzat, J. P. Fission yeast bub1 is a mitotic centromere protein essential for the spindle checkpoint and the preservation of correct ploidy through mitosis. J. Cell Abstract. The mitotic checkpoint is a specialized signal transduction pathway that contributes to the fidelity of chromosome segregation. The signaling of the checkpoint originates from defective kinetochore-microtubule interactions and leads to formation of the mitotic checkpoint complex (MCC), a highly potent inhibitor of the Anaphase Promoting Complex/Cyclosome (APC/C)โthe E3 ubiquitin
Taylor, S. S. et al. Kinetochore localisation and phosphorylation of the mitotic checkpoint components Bub1 and BubR1 are differentially regulated by spindle events in human cells. J. Cell Sci
Principles and dynamics of spindle assembly checkpoint signalling Biology Diagrams
The spindle checkpoint inhibits these APC/C functions by inactivating Cdc20 through the Mitotic Checkpoint Complex (MCC), which consists of Cdc20 in complex with Mad2, BubR1 (Mad3 in yeast), and Bub3 30. The MCC inactivates the APC/C through a variety of mechanisms 31-35 and is the biochemical manifestation of the "wait anaphase" signal. The spindle checkpoint ensures the fidelity of chromosome segregation by preventing cell-cycle progression until all the chromosomes make proper bipolar attachments to the mitotic spindle and come under tension. Despite significant advances in our understanding of spindle checkpoint function, the primary signal that activates the spindle checkpoint remains unclear. The spindle checkpoint is an evolutionarily conserved mitotic regulatory mechanism that ensures that anaphase is not attempted until chromosomes are properly aligned on the spindle. Two different cell-cycle transitions must be inhibited by the spindle checkpoint to arrest cells at metaphase and prevent mitotic exit. The checkpoint proteins interact in ways that are more complex than was
The mitotic spindle checkpoint. Gary J. Gorbsky. Biomedical Research Center, Room 266, 975 N.E. 10th St., University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA If the spindle checkpoint is defective (left pathway) then chromatid separation can occur before all the chromosomes are aligned at metaphase. The Abstract. In cells containing disrupted spindles, the spindle assembly checkpoint arrests the cell cycle in metaphase. The budding uninhibited by benzimidazole (Bub) 1, mitotic arrest-deficient (Mad) 1, and Mad2 proteins promote this checkpoint through sustained inhibition of the anaphase-promoting complex/cyclosome.
