Cyclin B is primarily known as Cyclin B1. This specific isoform is a critical protein involved in the regulation of the cell cycle.
Key Role in Cell Cycle Regulation
Cyclin B plays a pivotal role in controlling the progression of cells through the mitotic phase (M-phase) of the cell cycle. Its primary function is to activate cyclin-dependent kinase 1 (Cdk1), forming a complex known as the Maturation Promoting Factor (MPF), also referred to as the Mitosis Promoting Factor.
The MPF complex is essential for initiating and regulating key events in mitosis, including:
- Chromosome condensation: Preparing chromosomes for segregation.
- Nuclear envelope breakdown: Allowing access to the chromosomes.
- Spindle formation: Building the machinery for chromosome separation.
The levels of cyclin B fluctuate throughout the cell cycle, accumulating during the G2 phase and rapidly degrading during anaphase, which is crucial for the cell to exit mitosis and complete cell division.
Different Forms of Cyclin B
While Cyclin B1 is the most well-characterized and prominent form, other cyclin B isoforms exist, such as Cyclin B2 and Cyclin B3. These isoforms may have slightly different subcellular localizations or specific roles, but they generally contribute to the overall regulation of the G2/M transition and mitosis.
| Feature | Description |
|---|---|
| Primary Alias | Cyclin B1 |
| Binding Partner | Cyclin-dependent kinase 1 (Cdk1) |
| Formed Complex | Maturation Promoting Factor (MPF) / Mitosis Promoting Factor |
| Cell Cycle Phase | G2/M phase (Accumulates in G2, active in M, degraded in Anaphase) |
| Key Function | Regulates entry into and progression through mitosis by activating Cdk1. |
| Related Isoforms | Cyclin B2, Cyclin B3 |
For more detailed information on cyclin B and its structure, you can refer to resources like Cyclin B - Wikipedia.
