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Ubiquitination of full-length cyclin
D T Mahaffey1, Y Yoo, M Rechsteiner
1Department of Biochemistry, University of Utah, Salt Lake City 84132, USA.
FEBS Letters
|August 14, 1995
Summary
Ubiquitination, not cleavage, initiates cyclin destruction. Ubiquitin conjugates of Xenopus cyclin B2 suggest this process is key to cell-cycle regulation and proteolysis.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Mitotic cyclins are crucial for cell-cycle progression.
- Cyclin degradation is essential for timely cell division.
- The ubiquitin-proteasome system is implicated in protein turnover.
Purpose of the Study:
- To investigate the initial event in cyclin B2 destruction.
- To determine the role of ubiquitination in cyclin proteolysis.
Main Methods:
- Detection of ubiquitin conjugates of full-length Xenopus cyclin B2.
- Correlation of ubiquitin conjugate levels with proteolysis phases.
Main Results:
- Ubiquitin conjugates of cyclin B2 were detected, suggesting ubiquitination initiates degradation.
- Highest ubiquitin conjugate levels correlated with rapid proteolysis.
- Cyclin-ubiquitin conjugates were also observed in stable, non-degrading extracts.
Conclusions:
- Ubiquitination, rather than proteolytic cleavage, appears to initiate cyclin B2 destruction.
- The ubiquitin system plays a significant role in cyclin proteolysis.
- The function of ubiquitinated cyclin in arrested or interphase states requires further investigation.