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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

Cdc20 protein contains a destruction-box but, unlike Clb2, its proteolysisis not acutely dependent on the activity of

P Y Goh1, H H Lim, U Surana

  • 1Institute of Molecular Biology, Singapore.

European Journal of Biochemistry
|January 13, 2000
PubMed

Insights

The anaphase-promoting complex (APC) targets proteins for degradation during mitosis. This study reveals that Cdc20 degradation in G1 is independent of the APC, suggesting alternative degradation pathways for destruction-box proteins.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • The anaphase-promoting complex (APC/C) is crucial for chromosome segregation and mitotic exit by ubiquitinating substrates for proteasomal degradation.
  • Cdc20 is a key activator of APC/C-mediated proteolysis, essential for nuclear division in Saccharomyces cerevisiae.
  • APC/C-mediated ubiquitination requires a destruction-box motif in target proteins.

Purpose of the Study:

  • To investigate the cell-cycle regulation and degradation mechanisms of Cdc20.
  • To determine if APC/C is responsible for Cdc20 degradation during the G1 phase.

Main Methods:

  • Studied CDC20 gene expression patterns throughout the cell cycle.
  • Analyzed Cdc20 protein stability, particularly in G1 phase.
  • Investigated the effect of mutations in the Cdc20 destruction-box on its stability.
  • Examined the impact of inactivating APC subunits (Cdc16, Cdc23, Cdc27) on Cdc20 degradation.

Main Results:

  • CDC20 gene expression is restricted to late S phase and mitosis.
  • Cdc20 protein is degraded more rapidly during G1 phase.
  • Mutating or deleting the destruction-box of Cdc20 significantly stabilizes the protein in G1.
  • Inactivation of APC/C subunits did not affect the proteolytic destruction of Cdc20 in G1.

Conclusions:

  • Cdc20 degradation in G1 is regulated by its destruction-box motif.
  • The proteolytic degradation of Cdc20 in G1 occurs independently of the anaphase-promoting complex (APC/C).
  • This suggests the existence of APC/C-independent mechanisms for degrading destruction-box containing proteins during the G1 phase.

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