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[The characterization of human cdc2 kinase and CDK2]
1Faculty of Pharmaceutical Sciences, Kanazawa University, Ishikawa, Japan.
Yakugaku Zasshi : Journal of the Pharmaceutical Society of Japan
|December 1, 1993
Summary
cdc2 kinase and cyclin-dependent kinase 2 (CDK2) have distinct roles in the cell cycle. While cdc2 kinase initiates mitosis, CDK2 functions from G1 through M phase, phosphorylating different protein substrates.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- p34cdc2 kinase, complexed with cyclin A or B, initiates mitosis.
- The precise roles of cyclin A/cdc2 and cyclin B/cdc2 kinases remain unclear.
- Cyclin-dependent kinase 2 (CDK2) was identified as a cdc2-like kinase with a proposed G1 to S phase function.
Purpose of the Study:
- To separate and characterize human cyclin A/cdc2 kinase, cyclin B/cdc2 kinase, and CDK2.
- To elucidate the distinct substrate specificities and cell cycle roles of these kinases.
Main Methods:
- Column chromatography was used to isolate individual kinases.
- Kinase activity was assessed using synthesized peptides and native proteins.
- Cell cycle progression and kinase activity were monitored in human cells.
Main Results:
- All tested kinases phosphorylated threonine residues in specific peptide sequences (-Thr-Pro-Lys-Lys-Ala-).
- Differences in substrate preference were observed when using native proteins.
- cdc2 kinase activity peaked during the G2/M phase, while CDK2 activity was high from S through M phase.
Conclusions:
- cdc2 kinase likely functions at the G2/M phase transition.
- CDK2 appears to be active throughout the cell cycle, from G1 to M phase.
- These kinases phosphorylate distinct protein substrates containing a common -Thr-Pro-X-Lys- motif.