Apc/c

Definition

apc/c, or the Anaphase Promoting Complex/Cyclosome, is a multi-subunit E3 ubiquitin ligase that plays a critical role in the regulation of the cell cycle. It marks specific proteins for degradation, particularly those involved in cell cycle progression, thereby ensuring the orderly transition through mitosis and maintaining genomic stability. Its function is essential for processes like chromosome segregation and the exit from mitosis, linking post-translational modifications to cell cycle control.

5 Must Know Facts For Your Next Test

1. apc/c is activated at the onset of anaphase, playing a crucial role in ensuring that sister chromatids separate properly during cell division.
2. It targets key regulatory proteins such as securin and cyclins for ubiquitination and subsequent degradation, which is vital for the transition from metaphase to anaphase.
3. The proper functioning of apc/c is necessary to prevent errors in chromosome segregation, which can lead to aneuploidy and contribute to cancer development.
4. apc/c activity is tightly regulated by various factors, including CDKs and checkpoint proteins, to ensure that it functions correctly during the cell cycle.
5. Mutations or dysregulation of apc/c have been linked to several human diseases, particularly cancer, highlighting its importance in maintaining cellular homeostasis.

Review Questions

• How does apc/c influence the regulation of the cell cycle, particularly during mitosis?
  • apc/c influences the regulation of the cell cycle by marking specific proteins for degradation during mitosis. This process is crucial for ensuring that cyclins are broken down at the appropriate time, allowing for the transition from metaphase to anaphase. By targeting securin for degradation, apc/c facilitates the separation of sister chromatids, thereby maintaining genomic stability throughout cell division.
• Discuss the implications of dysregulated apc/c activity in relation to human diseases such as cancer.
  • Dysregulated apc/c activity can lead to improper protein degradation and disrupted cell cycle progression, which are significant contributors to tumorigenesis. For instance, if apc/c fails to degrade cyclins appropriately, cells may continue to progress through the cell cycle unchecked, resulting in uncontrolled proliferation. Additionally, mutations in genes encoding components of apc/c have been associated with various cancers, emphasizing its critical role in preventing malignancies.
• Evaluate the importance of post-translational modifications facilitated by apc/c in maintaining cellular integrity and function.
  • Post-translational modifications facilitated by apc/c are essential for maintaining cellular integrity and function by regulating key proteins involved in cell cycle progression. By ensuring timely degradation of specific proteins through ubiquitination, apc/c prevents errors in chromosome segregation and supports proper cellular responses to stress or damage. The intricate balance maintained by apc/c illustrates how post-translational modifications are integral not only for cell division but also for overall cellular health and preventing diseases such as cancer.

Related terms

Ubiquitination: A post-translational modification that involves attaching ubiquitin to a protein, marking it for degradation by the proteasome.

Cyclins: Regulatory proteins that control the progression of the cell cycle by activating cyclin-dependent kinases (CDKs) through periodic synthesis and degradation.

Proteasome: A large protein complex that degrades unneeded, damaged, or misfolded proteins by breaking them down into smaller peptides.