Human BUB1 knockout HeLa cell lysate

Supplementary info

This supplementary information is collated from multiple sources and compiled automatically.

Activity summary

Bub1 protein often referred to as 'Bub1' plays a mechanical role in cell cycle regulation especially during mitosis. It is known by other names such as BUB1 mitotic checkpoint serine/threonine kinase. Bub1 has a molecular mass of approximately 120 kDa. This protein is expressed in various tissues with higher levels in rapidly dividing cells. The location of its action is mainly the nucleus where it associates with kinetochores during cell division functioning in the spindle assembly checkpoint.

Biological function summary

Bub1 protein acts as a serine/threonine-protein kinase that is essential for proper chromosome segregation. It forms part of the spindle checkpoint complex along with other proteins such as BubR1 and Mad2. This complex ensures that chromosomes are correctly attached to the spindle microtubules before anaphase begins. Bub1's kinase activity contributes to the prevention of premature anaphase onset thereby helping maintain genomic stability.

Pathways

Bub1 is significantly involved in the mitotic checkpoint pathway and the cell cycle control pathway. Within these pathways Bub1 interacts closely with proteins like CDC20 and APC/C which are integral parts of the anaphase-promoting complex. Bub1 modifies the activity of these proteins to delay anaphase onset until all chromosomes are properly aligned ensuring the fidelity of cell division.

Associated diseases and disorders

Bub1 protein shows a connection to various cancer types notably breast cancer and colorectal cancer. Defects or overexpression in Bub1 can disrupt the spindle assembly checkpoint leading to chromosome missegregation and aneuploidy hallmarks of cancerous cells. Bub1 is also linked to other spindle checkpoint proteins such as Mad1 and Bub3. Malfunction in any of these proteins including Bub1 can contribute to tumorigenesis due to impaired cell cycle control.