Related Experiment Video

Updated: Aug 4, 2026

Studying Proteolysis of Cyclin B at the Single Cell Level in Whole Cell Populations
10:54

Studying Proteolysis of Cyclin B at the Single Cell Level in Whole Cell Populations

Published on: September 17, 2012

Phosphorylation of Cdc20/fizzy negatively regulates the mammalian cyclosome/APC in the mitotic checkpoint

Y Yudkovsky1, M Shteinberg, T Listovsky

  • 1Unit of Biochemistry, B. Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, 31096, Israel.

Biochemical and Biophysical Research Communications
|May 9, 2000
PubMed

Insights

Phosphorylation of Cdc20 by Cdk1/cyclin B inhibits the anaphase-promoting complex (APC). This inhibitory phosphorylation of Cdc20 may prevent premature APC activation during early mitosis and mitotic arrest.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • The anaphase-promoting complex (APC/C) is a crucial ubiquitin ligase regulating cell cycle progression.
  • APC/C activity is tightly controlled by regulatory proteins like Cdc20 and Cdh1.
  • The role of Cdc20 phosphorylation in regulating APC/C activity remained unclear.

Purpose of the Study:

  • To investigate the function of Cdc20 phosphorylation by Cdk1/cyclin B.
  • To determine the impact of Cdc20 phosphorylation on APC/C activation.

Main Methods:

  • Using mitotic HeLa cells and cell extracts.
  • Employing a nonphosphorylatable Cdc20 derivative.
  • Assessing cyclin-ubiquitin ligation activity.

Main Results:

  • Phosphorylation of Cdc20 by Cdk1/cyclin B abrogates its ability to activate APC/C.
  • A nonphosphorylatable Cdc20 derivative significantly enhanced APC/C activity in cell extracts.
  • Mitotic HeLa cell Cdc20 is phosphorylated by Cdk1/cyclin B.

Conclusions:

  • Inhibitory phosphorylation of Cdc20 by Cdk1/cyclin B plays a role in maintaining APC/C inactivity.
  • This mechanism likely contributes to regulating APC/C activity during early mitosis and mitotic checkpoint arrest.

More Related Videos

Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay12:26

Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay

Published on: May 3, 2018

Manipulation and Analysis of Cell Cycle-Dependent Processes in Budding Yeast08:13

Manipulation and Analysis of Cell Cycle-Dependent Processes in Budding Yeast

Published on: September 26, 2025

Related Concept Videos

Positive Regulator Molecules01:45

Positive Regulator Molecules

To consistently produce healthy cells, the cell cycle—the process that generates daughter cells—must be precisely regulated.
Positive Regulator Molecules02:39

Positive Regulator Molecules

Mitotic cell division results in daughter cells that exactly resemble the parent cell. However, errors in the DNA replication or distribution of genetic material may lead to genetic mutations that may be passed down to every new cell formed from the resulting abnormal cell. Propagation of such mutant cells is restricted through checkpoint mechanisms present at different stages of the cell cycle. These checkpoints involve regulator molecules that either promote or demote cell cycle events.
Inhibition of Cdk Activity02:34

Inhibition of Cdk Activity

The orderly progression of the cell cycle depends on the activation of Cdk protein by binding to its cyclin partner. However, the cell cycle must be restricted when undergoing abnormal changes. Most cancers correlate to the deregulated cell cycle, and since Cdks are a central component of the cell cycle, Cdk inhibitors are extensively studied to develop anticancer agents. For instance, cyclin D associates with several Cdks, such as Cdk 4/6, to form an active complex. The cyclin D-Cdk4/6 complex...
Separation of Sister Chromatids02:17

Separation of Sister Chromatids

At the transition from prophase to metaphase, there is a reduction in cohesion along the chromosomal arms, resulting in the resolution of sister chromatids. However, residual cohesin connections remain to hold the sister chromatids together until the transition from metaphase to anaphase. The residual connection prevents any premature separation of sister chromatids, blocking the risks of aneuploidy within the daughter cells.
At the onset of anaphase, separase, a proteolytic enzyme, is...
Anaphase Promoting Complex00:50

Anaphase Promoting Complex

The stepwise destruction of specific proteins is necessary for the progression and completion of the cell cycle. Such proteins are ubiquitinated by ubiquitin ligases and then subsequently destroyed by the proteasome. The SCF (Skp1/Cullin/F-box) and the anaphase-promoting complex (APC) are two important ubiquitin ligases involved in cell cycle progression. While SCF is active throughout the cell cycle, APC gets activated during metaphase to anaphase transition. Cdc20 or Cdh1 binds to APC and...
Anaphase Promoting Complex00:50

Anaphase Promoting Complex

The stepwise destruction of specific proteins is necessary for the progression and completion of the cell cycle. Such proteins are ubiquitinated by ubiquitin ligases and then subsequently destroyed by the proteasome. The SCF (Skp1/Cullin/F-box) and the anaphase-promoting complex (APC) are two important ubiquitin ligases involved in cell cycle progression. While SCF is active throughout the cell cycle, APC gets activated during metaphase to anaphase transition. Cdc20 or Cdh1 binds to APC and...