regulation of cell cycle phase transition

Definition

Target type: biologicalprocess

Any process that modulates the frequency, rate or extent of cell cycle phase transition. [GOC:mtg_cell_cycle, GOC:TermGenie, PMID:22841721]

The cell cycle is a tightly regulated process that ensures the accurate duplication and distribution of the genome to daughter cells. Transition between the different phases of the cell cycle - G1, S, G2, and M - is controlled by a complex network of regulatory proteins, including cyclins and cyclin-dependent kinases (CDKs).

Cyclins are regulatory proteins that fluctuate in concentration throughout the cell cycle. They bind to and activate CDKs, which are protein kinases that phosphorylate target proteins involved in cell cycle progression. Different cyclins are expressed at different stages of the cell cycle, and their association with specific CDKs drives the transition between phases.

In G1 phase, the cell grows and synthesizes proteins needed for DNA replication. The G1/S checkpoint ensures that the cell is ready to enter S phase and replicates its DNA accurately. This checkpoint is controlled by cyclin D and CDK4/6, which phosphorylate the retinoblastoma protein (Rb). Rb normally inhibits the expression of genes required for DNA replication, but when phosphorylated, it releases these genes, allowing the cell to progress into S phase.

S phase is characterized by DNA replication. Cyclin A and CDK2 are the major players in this phase, promoting the activation of DNA replication machinery and ensuring the correct duplication of the genome.

After S phase, the cell enters G2, where it continues to grow and prepare for mitosis. G2 is also a checkpoint phase, ensuring the completion of DNA replication and the integrity of the genome before entering mitosis. Cyclin B and CDK1 are the key regulators of G2/M transition. They activate various proteins required for mitotic entry, including the proteins that condense chromosomes and form the mitotic spindle.

M phase is the stage of cell division, comprising mitosis and cytokinesis. Cyclin B and CDK1 remain active throughout mitosis, promoting the progression of the different stages of mitosis, including chromosome alignment, separation, and the formation of the contractile ring that divides the cytoplasm.

The cell cycle is regulated not only by positive regulators like cyclins and CDKs, but also by negative regulators like CDK inhibitors (CKIs). CKIs bind to and inhibit the activity of CDKs, preventing premature progression through the cell cycle.

In summary, the transition between cell cycle phases is a complex and tightly regulated process driven by the interplay of cyclins, CDKs, and CDK inhibitors. These regulatory proteins ensure the proper execution of each phase of the cell cycle, ensuring accurate DNA replication and chromosome segregation.'
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Proteins (1)

Compounds (6)