RYBP-PRC1 Complexes Mediate H2A Ubiquitylation at Polycomb Target Sites Independently of PRC2 and H3K27me3 Lı´gia Tavares,1 Emilia Dimitrova,2 David Oxley,3 Judith Webster,3 Raymond Poot,4 Jeroen Demmers,5 Karel Bezstarosti,5 Stephen Taylor,6 Hiroki Ura,7 Hiroshi Koide,7 Anton Wutz,8 Miguel Vidal,9 Sarah Elderkin,2,* and Neil Brockdorff1,* 1Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK 2Nuclear Dynamics 3Mass Spectrometry Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK 4Department of Cell Biology 5Proteomics Center Erasmus Medical Center, Dr. Molewaterplein 50, 3015GE Rotterdam, The Netherlands 6Computational Biology Research Group, WIMM, University of Oxford, John Radcliffe Hospital, Headington, Oxford OX3 9DS, UK 7Department of Stem Cell Biology, Graduate School of Medical Science, Kanazawa University, 13-1 Takaramachi, Kanazawa, Ishikawa 920-8640, Japan 8Wellcome Trust Centre for Stem Cell Research, Tennis Court Road, Cambridge CB2 1QR, UK 9Cell Proliferation and Development, Centro de Investigaciones Biolo´ gicas, Consejo Superior de Investigaciones Cientificas (CSIC), 28040 Madrid, Spain *Correspondence:
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[email protected] (N.B.) DOI 10.1016/j.cell.2011.12.029 SUMMARY histone-modifying activity critical for their function in gene re- pression, monoubiquitylation of histone H2AK119 (H2AK119u1), Polycomb-repressive complex 1 (PRC1) has a central and di- tri-methylation of histone H3K27, respectively (reviewed role in the regulation of heritable gene silencing in Mu¨ ller and Verrijzer, 2009). Mechanisms other than H2A during differentiation and development. PRC1 re- ubiquitylation also contribute to PRC1-mediated gene repression cruitment is generally attributed to interaction of (Eskeland et al., 2010; Francis et al., 2001, 2004; King et al., 2002; the chromodomain of the core protein Polycomb Shao et al., 1999).