Related Experiment Video

Updated: Jun 11, 2026

In Vitro Analysis of E3 Ubiquitin Ligase Function
06:06

In Vitro Analysis of E3 Ubiquitin Ligase Function

Published on: May 14, 2021

Mechanisms of ubiquitylation of the mitotic regulatory protein Cdc20

Danielle Sitry-Shevah1, Shirly Miniowitz-Shemtov1, Tania Liburkin Dan1

  • 1Department of Biochemistry, The Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 31096, Israel.

Proceedings of the National Academy of Sciences of the United States of America
|June 9, 2026
PubMed

Insights

The anaphase-promoting complex/cyclosome (APC/C) ubiquitin ligase targets Cdc20 for degradation. This study reveals that Cdc20 ubiquitylation involves a trans mechanism, requiring its IR tail and degrons for APC/C interaction.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • The anaphase-promoting complex/cyclosome (APC/C) is a crucial E3 ubiquitin ligase regulating cell cycle progression, particularly mitosis.
  • Cdc20 acts as a co-activator for the APC/C during mitosis, and its own degradation is essential for cell cycle exit.
  • Previous models proposed an intramolecular (cis) mechanism for Cdc20 ubiquitylation by APC/C.

Purpose of the Study:

  • To investigate the mechanism of Cdc20 ubiquitylation by the APC/C.
  • To determine the role of the Cdc20 IR tail in its ubiquitylation by different APC/C co-activators.
  • To elucidate the interaction model between APC/C, co-activators, and substrates like Cdc20.

Main Methods:

  • Investigated the role of the Cdc20 IR tail in ubiquitylation mediated by both APC/C^Cdc20 and APC/C^Cdh1.
  • Analyzed the requirement of KEN-box and CRY-box degrons in Cdc20 ubiquitylation.
  • Proposed a molecular model for substrate recognition and ubiquitylation by APC/C complexes.

Main Results:

  • The IR tail of Cdc20 is essential for its ubiquitylation by both APC/C^Cdc20 and APC/C^Cdh1, suggesting a trans mechanism.
  • Cdc20 ubiquitylation by both co-activator complexes requires its KEN-box and CRY-box degrons.
  • A model is proposed where the IR tail, KEN-box, and CRY-box of Cdc20 interact with APC/C-coactivator complexes.

Conclusions:

  • Cdc20 ubiquitylation by the APC/C occurs via a trans mechanism, challenging previous cis-mechanism models.
  • The IR tail, along with KEN-box and CRY-box motifs, plays a critical role in substrate recognition and ubiquitylation by APC/C.
  • This finding provides a refined understanding of APC/C substrate targeting and cell cycle regulation.
Keywords:
cell cyclemitosisubiquitin

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