3gs2 | pdb_00003gs2
Ring1B C-terminal domain/Cbx7 Cbox Complex
Structural highlights
Function[RING2_HUMAN] E3 ubiquitin-protein ligase that mediates monoubiquitination of 'Lys-119' of histone H2A, thereby playing a central role in histone code and gene regulation. H2A 'Lys-119' ubiquitination gives a specific tag for epigenetic transcriptional repression and participates in X chromosome inactivation of female mammals. May be involved in the initiation of both imprinted and random X inactivation. Essential component of a Polycomb group (PcG) multiprotein PRC1-like complex, a complex class required to maintain the transcriptionally repressive state of many genes, including Hox genes, throughout development. PcG PRC1 complex acts via chromatin remodeling and modification of histones, rendering chromatin heritably changed in its expressibility. E3 ubiquitin-protein ligase activity is enhanced by BMI1/PCGF4. Acts as the main E3 ubiquitin ligase on histone H2A of the PRC1 complex, while RING1 may rather act as a modulator of RNF2/RING2 activity.[1] [2] [3] [4] [5] [CBX7_HUMAN] Component of a Polycomb group (PcG) multiprotein PRC1-like complex, a complex class required to maintain the transcriptionally repressive state of many genes, including Hox genes, throughout development. PcG PRC1 complex acts via chromatin remodeling and modification of histones; it mediates monoubiquitination of histone H2A 'Lys-119', rendering chromatin heritably changed in its expressibility. Promotes histone H3 trimethylation at 'Lys-9' (H3K9me3). Binds to trimethylated lysine residues in histones, and possibly also other proteins. Regulator of cellular lifespan by maintaining the repression of CDKN2A, but not by inducing telomerase activity.[6] [7] [8] [9] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedRING1B, 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. Polycomb group targeting through different binding partners of RING1B C-terminal domain.,Wang R, Taylor AB, Leal BZ, Chadwell LV, Ilangovan U, Robinson AK, Schirf V, Hart PJ, Lafer EM, Demeler B, Hinck AP, McEwen DG, Kim CA Structure. 2010 Aug 11;18(8):966-75. PMID:20696397[10] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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