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Updated: Jun 19, 2026

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In Vitro Analysis of E3 Ubiquitin Ligase Function
Published on: May 14, 2021
Ring1B contains a ubiquitin-like docking module for interaction with Cbx proteins.
Irina Bezsonova1, John R Walker, John P Bacik
1Structural Genomics Consortium, University of Toronto, 101 College Street, Toronto, Ontario, M5G 1L5, Canada.
Biochemistry
|October 2, 2009
Summary
Polycomb repressive complex 1 (PRC1) Ring1B protein
Area of Science:
- Epigenetics
- Molecular Biology
- Structural Biology
Background:
- Polycomb group (PcG) proteins regulate gene expression through epigenetic modifications.
- Polycomb repressive complex 1 (PRC1) maintains gene silencing via histone H2A K119 ubiquitylation.
- PRC1 subunits, including Ring1B, interact with Cbx proteins for chromatin binding.
Purpose of the Study:
- To elucidate the structural basis of Ring1B's function within PRC1.
- To investigate the interaction mechanisms of Ring1B with Cbx proteins and homodimerization.
Main Methods:
- High-resolution crystal structure determination of the Ring1B C-terminal domain.
- Mutational analysis to assess the functional significance of conserved surface regions.
Main Results:
- The Ring1B C-terminal domain adopts a ubiquitin-like fold with a unique conserved surface.
- This conserved surface mediates interactions with Cbx proteins and facilitates Ring1B homodimerization.
- Ring1B acts as an adaptor linking PRC1 components and the nucleosome.
Conclusions:
- Ring1B's structure reveals its role as a crucial adaptor in the PRC1 complex.
- Understanding Ring1B structure-function relationships provides insights into epigenetic gene regulation.
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