Related Experiment Video

Updated: Jun 4, 2025

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

10.5K

A phosphate-binding pocket in cyclin B3 is essential for XErp1/Emi2 degradation in meiosis I

Rebecca Schunk1,2, Marc Halder1,2, Michael Schäfer1

  • 1Department of Biology, University of Konstanz, 78457, Konstanz, Germany.

EMBO Reports
|January 3, 2025
PubMed

Insights

A novel phosphate-binding pocket in cyclin B3 is key for degrading XErp1/Emi2, preventing premature oocyte arrest during meiosis I. This ensures proper fertilization and embryo development.

Area of Science:

  • Cell Biology
  • Developmental Biology
  • Molecular Biology

Background:

  • Vertebrate oocyte arrest at meiosis II is crucial for correct ploidy, regulated by XErp1/Emi2 inhibiting APC/C.
  • Cyclin B3/Cdk1 complex prevents premature meiosis I arrest by degrading XErp1/Emi2, but the mechanism is unclear.

Purpose of the Study:

  • To elucidate the molecular mechanism of XErp1/Emi2 degradation during meiosis I.
  • To identify novel determinants of cyclin B3 substrate specificity.

Main Methods:

  • TRIM-Away technique in oocytes
  • Xenopus egg extract experiments
  • In vitro biochemical assays

Main Results:

  • A previously unknown phosphate-binding pocket in cyclin B3 is essential for XErp1/Emi2 degradation in meiosis I.
  • Cdk1/cyclin B3 utilizes this pocket to bind pre-phosphorylated XErp1/Emi2, promoting further phosphorylation and degradation via Plk1.
  • This mechanism is conserved in frog and mouse oocytes.

Conclusions:

  • Identified a novel, evolutionarily conserved mechanism regulating XErp1/Emi2 degradation.
  • Discovered a new determinant of Cdk/cyclin substrate specificity crucial for preventing aberrant oocyte arrest at meiosis I.
  • This finding has implications for understanding fertilization and embryonic development.
Keywords:
APC/CCyclin B3Emi2Phosphate-binding PocketXErp1

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

18.5K
Use of Time-Lapse Microscopy and Stage-Specific Nuclear Depletion of Proteins to Study Meiosis in S. cerevisiae07:48

Use of Time-Lapse Microscopy and Stage-Specific Nuclear Depletion of Proteins to Study Meiosis in S. cerevisiae

Published on: October 11, 2022

1.8K

Related Concept Videos

Meiosis II02:02

Meiosis II

Meiosis II entails cell division and segregation of the sister chromatids, resulting in the production of four unique haploid gametes. The steps for meiosis II are similar to mitosis, except that meiosis II occurs in haploid cells, whereas mitosis occurs in diploid cells.
The timing and cell division patterns of meiosis differ between males and females. In male meiosis, the centrosomes are part of the formation of the meiotic spindle. However, in oocytes, including that of humans, Drosophila,...
43.1K
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...
2.8K
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...
3.6K
M-Cdk Drives Transition Into Mitosis02:15

M-Cdk Drives Transition Into Mitosis

Checkpoints throughout the cell cycle serve as safeguards and gatekeepers, allowing the cell cycle to progress in favorable conditions and slow or halt it in problematic ones. This regulation is known as the cell cycle control system.
Cyclin-dependent kinases, or Cdks, work in concert with cyclins to control cell cycle transitions. M-Cdk, a complex of Cdk1 bound to M cyclin, is a well-known example of this coordinated control that drives the transition from the G2 to the M phase.
M cyclin...
5.5K
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.
5.3K
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...
4.6K