During which phase of the cell cycle is cyclin B1 degraded?

The degradation of cyclin B1 occurs during the transition from metaphase to anaphase, marking the end of mitosis. Cyclin B1 is a part of the cyclin-dependent kinase 1 (CDK1) complex, which is crucial for the progression through mitosis. During metaphase, cyclin B1 levels peak to ensure that the cell is prepared to transition smoothly into anaphase. As cells move into anaphase, cyclin B1 is ubiquitinated and then targeted for degradation by the proteasome, leading to a decrease in CDK1 activity. This degradation is essential for allowing the cell to exit mitosis and begin the process of cytokinesis and return to interphase.

Understanding this degradation process helps illustrate the tightly regulated nature of the cell cycle, where specific proteins like cyclins are utilized at various stages to control the progression and ensure proper cell division.