metaphase/anaphase transition of cell cycle

Definition

Target type: biologicalprocess

The cell cycle process in which a cell progresses from metaphase to anaphase as part of the cell cycle. [GOC:mtg_cell_cycle]

The metaphase/anaphase transition is a critical juncture in the cell cycle, marking the completion of chromosome alignment and the initiation of sister chromatid separation. This transition is orchestrated by a tightly controlled cascade of events, ensuring accurate chromosome segregation.

**1. Checkpoint Activation and APC/C Activation:**
- The mitotic spindle checkpoint ensures that all chromosomes are properly attached to the spindle microtubules before the transition.
- Upon successful attachment, the checkpoint is deactivated, leading to the activation of the Anaphase Promoting Complex/Cyclosome (APC/C).

**2. Securin Degradation and Separase Activation:**
- Activated APC/C targets securin for ubiquitination and proteasomal degradation.
- Securin normally inhibits the protease separase. Its degradation releases separase, allowing it to cleave cohesin.

**3. Cohesin Cleavage and Sister Chromatid Separation:**
- Cohesin is a protein complex that holds sister chromatids together.
- Separase cleaves cohesin, releasing the sister chromatids from each other.
- The freed sister chromatids are pulled to opposite poles of the cell by the spindle microtubules.

**4. Cytokinesis Initiation:**
- The metaphase/anaphase transition also triggers the formation of the contractile ring, a structure composed of actin and myosin filaments.
- This ring contracts, ultimately leading to the division of the cytoplasm and the formation of two daughter cells.

**5. Regulation of the Transition:**
- The metaphase/anaphase transition is tightly regulated by a complex network of signaling pathways involving proteins like cyclin B, CDK1, and Mad2.
- This regulation ensures that the transition occurs only when the cell is ready and that errors in chromosome segregation are minimized.'
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Proteins (1)

Compounds (1)