Related Experiment Videos
Threonine phosphorylation is associated with mitosis in HeLa cells
J Y Zhao1, J Kuang, R C Adlakha
1Department of Medical Oncology, University of Texas M.D. Anderson Cancer Center, Houston.
FEBS Letters
|June 5, 1989
Summary
Protein phosphorylation regulates cell division. This study found that threonine phosphorylation is a key event during the G2-M transition, while serine phosphorylation occurs throughout the cell cycle. Threonine dephosphorylation marks the end of mitosis.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Protein phosphorylation and dephosphorylation are crucial for regulating mitosis and meiosis.
- The mitosis-specific monoclonal antibody MPM-2 recognizes phosphopeptides present in mitotic cells.
- These phosphopeptides are synthesized in S phase and phosphorylated during the G2/mitosis transition.
Purpose of the Study:
- To identify the specific amino acids phosphorylated during the G2-mitosis (M) transition.
- To investigate the role of phosphorylation in cell cycle regulation.
Main Methods:
- Raised a polyclonal antibody against a 55 kDa protein recognized by MPM-2.
- Performed phosphoamino acid analysis on 32P-labeled HeLa cell extracts.
- Utilized immunoprecipitation with anti-p55 antibodies.
Main Results:
- Threonine was extensively phosphorylated in p55 during G2-M transition but not in S phase.
- Serine was phosphorylated during both S and M phases; tyrosine was not phosphorylated.
- Phosphothreonine was completely dephosphorylated upon entry into G1 phase, while phosphoserine was not.
Conclusions:
- Phosphorylation of threonine appears to be specific to certain mitosis-related events.
- These findings contribute to understanding the molecular mechanisms regulating cell division.