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Ubiquitin Chain Analysis by Parallel Reaction Monitoring
Published on: June 17, 2020
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Deciphering functions of branched ubiquitin chains.
Jaime López-Mosqueda1, Ivan Dikic1
1Institute of Biochemistry II, Goethe University, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany.
Cell
|May 13, 2014
Summary
The anaphase-promoting complex/cyclosome (APC/C) targets proteins for degradation. This study shows APC/C and E2 enzymes create branched ubiquitin chains, speeding up protein destruction.
Area of Science:
- Cellular biology
- Molecular biology
- Biochemistry
Background:
- The anaphase-promoting complex/cyclosome (APC/C) is a crucial ubiquitin ligase complex.
- APC/C regulates cell cycle progression by targeting key proteins for degradation.
- Ubiquitination, particularly through K48-linked chains, signals proteins for proteasomal degradation.
Purpose of the Study:
- To investigate the role of different ubiquitin chain linkages in APC/C-mediated protein degradation.
- To explore how APC/C and its associated enzymes generate diverse ubiquitin chain architectures.
- To understand the impact of branched ubiquitin chains on the rate of substrate degradation.
Main Methods:
- Biochemical assays to monitor ubiquitination.
- Analysis of ubiquitin chain topology using mass spectrometry.
- In vitro degradation assays with purified APC/C and E2 enzymes.
Main Results:
- APC/C, with E2 conjugating enzymes, synthesizes branched ubiquitin chains.
- Both Lys11 (K11) and Lys48 (K48) linkages are utilized in these branched structures.
- Branched K11/K48 ubiquitin chains accelerate the degradation of APC/C substrates.
Conclusions:
- Branched ubiquitin chains represent a sophisticated degradation signal.
- The combination of K11 and K48 linkages enhances degradation efficiency.
- This mechanism provides a more nuanced control over protein turnover during the cell cycle.
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