Related Experiment Video

Updated: Apr 19, 2026

Combining Mitotic Cell Synchronization and High Resolution Confocal Microscopy to Study the Role of Multifunctional Cell Cycle Proteins During Mitosis
08:33

Combining Mitotic Cell Synchronization and High Resolution Confocal Microscopy to Study the Role of Multifunctional Cell Cycle Proteins During Mitosis

Published on: December 5, 2017

15.1K

The activity regulation of the mitotic centromere-associated kinesin by Polo-like kinase 1

Andreas Ritter1, Mourad Sanhaji1,2, Kerstin Steinhäuser1

  • 1Department of Gynecology and Obstetrics, School of Medicine, J. W. Goethe-University, 60590 Frankfurt, Germany.

Oncotarget
|December 16, 2014
PubMed

Insights

Polo-like kinase 1 (Plk1) regulates mitotic centromere-associated kinesin (MCAK) degradation via S621 phosphorylation. Plk1 also modulates MCAK activity through S632/S633 phosphorylation, crucial for spindle assembly and chromosome alignment.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Mitotic centromere-associated kinesin (MCAK) is a key microtubule depolymerase regulating spindle dynamics.
  • Polo-like kinase 1 (Plk1) phosphorylates MCAK, controlling its activity and localization during mitosis.
  • Previous work identified S621 as a Plk1 phosphorylation site regulating MCAK degradation.

Purpose of the Study:

  • To investigate the role of Plk1 phosphorylation at S632/S633 residues in MCAK function during mitosis.
  • To elucidate the distinct regulatory mechanisms of MCAK by Plk1 phosphorylation at different sites.

Main Methods:

  • Site-directed mutagenesis to alter S632/S633 residues.
  • In vitro kinase assays to assess Plk1 activity on MCAK.
  • Microscopy to observe spindle assembly and chromosome alignment in cells expressing modified MCAK.

Main Results:

  • Plk1 phosphorylates S632/S633 in the C-terminus of MCAK.
  • Phosphorylation of S632/S633 regulates MCAK's catalytic activity during mitosis.
  • This phosphorylation is essential for proper spindle assembly in early mitosis.
  • Dephosphorylation of S632/S633 appears necessary for chromosome alignment at the metaphase plate.

Conclusions:

  • Plk1 employs distinct phosphorylation sites on MCAK to control both its degradation (S621) and its catalytic activity (S632/S633).
  • Plk1-mediated phosphorylation of S632/S633 is critical for accurate spindle formation and chromosome segregation during cell division.
Keywords:
MCAKPlk1chromosome alignmentphosphorylationspindle assembly

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

19.5K
Quantitative Immunofluorescence Assay to Measure the Variation in Protein Levels at Centrosomes09:39

Quantitative Immunofluorescence Assay to Measure the Variation in Protein Levels at Centrosomes

Published on: December 20, 2014

15.9K

Related Concept Videos

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...
6.8K
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...
3.6K
Anaphase Promoting Complex00:50

Anaphase Promoting Complex

1.9K
Attachment of Sister Chromatids02:57

Attachment of Sister Chromatids

As cells progress into mitosis, the nuclear envelope breaks down, and the condensed chromosomes are exposed to the array of bipolar microtubules of the mitotic spindle. The kinetochore, a large, disc-shaped protein complex, is present at the centromere region of the sister chromatids and acts as a binding site for the microtubules.  Usually, the plus-end of a single microtubule is embedded within the kinetochore. However, some kinetochores first establish lateral contact with the side-wall...
4.2K
Destabilization of Microtubules01:45

Destabilization of Microtubules

The destabilization of microtubules can occur during different stages of the microtubule lifecycle, such as nucleation or elongation. It can take place at either end of the microtubule or in the microtubule lattices as a whole. The lifespan of individual microtubules within a cell varies according to the cell type and stage of the cell cycle. During interphase, the lifespan of the microtubule is about 30 minutes, while during cell division, it is about 15 minutes. In axonal microtubules of...
3.9K
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...
4.8K