3GS2: Ring1b C-Terminal DomainCBX7 CBOX COMPLEX

RING1B, a Polycomb Group (PcG) protein, binds methylated chromatin through its association with another PcG protein called Polycomb (Pc). However, RING1B can associate with nonmethylated chromatin suggesting an alternate mechanism for RING1B interaction with chromatin. Here, we demonstrate that two proteins with little sequence identity between them, the Pc cbox domain and RYBP, bind the same surface on the C-terminal domain of RING1B (C-RING1B). Pc cbox and RYBP each fold into a nearly identical, intermolecular beta sheet with C-RING1B and a loop structure which are completely different in the two proteins. Both the beta sheet and loop are required for stable binding and transcription repression. Further, a mutation engineered to disrupt binding on the Drosophila dRING1 protein prevents chromatin association and PcG function in vivo. These results suggest that PcG targeting to different chromatin locations relies, in part, on binding partners of C-RING1B that are diverse in sequence and structure.
PDB ID: 3GS2Download
MMDB ID: 84348
PDB Deposition Date: 2009/3/26
Updated in MMDB: 2010/08
Experimental Method:
x-ray diffraction
Resolution: 1.7  Å
Source Organism:
Similar Structures:
Biological Unit for 3GS2: dimeric; determined by author and by software (PISA)
Molecular Components in 3GS2
Label Count Molecule
Proteins (2 molecules)
E3 Ubiquitin-protein Ligase Ring2(Gene symbol: RNF2)
Molecule annotation
Chromobox Protein Homolog 7(Gene symbol: CBX7)
Molecule annotation
Chemicals (3 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB