E3 ligase

nullnullnullIntroduction ●Polycomb group(PcG) repressor proteins At least two multiprotein complex:PRC1 and PRC2 ●PRC1 core components in D. melanogaster PC:Polycomb PSC:Posterior sex combs PH:Polyhomeotic RING1●PRC1-like complex Former: Bmi 1 containing PRC1-like complex (Wang et al., 2004). In this paper:mel-18 containing PRC1-like complexnullTandem affinity purification(TAP) of Mel-18 and Bmi1 associated polycomb proteinsRING1 CBX8 RING2 HPH2aComponents of PRC1-like Complex,and this complex containing BMI1 function as a E3 Ligase specifically monoubiquitylates H2A K119nullnullnullnullnullnullnullnullResults in summaryidentifying human and mouse PRC1-like complexes containing Mel-18 (melPRC1) melPRC1 and bmiPRC1 complex function distinctly although they share common subunits subcomplex of melPRC1 comprising Mel-18 and Ring1B is an efficient E3 ligase in vitro and ubiquitylates H2A lysine 119 in chromatin Ring1B plays a direct role in the ubiquitylation reaction but needs mel-18 targets it to chromatin nucleosomal targeting of melPRC1 requires prior phosphorylation of Mel -18 Results in summary Discussion Discussion Functional Interchangeability of PRC1-like Complexes Mechanism of H2A Lysine 119 Ubiquitylation Regulation of Polycomb Complexes by Phosphorylation forwardnullRing 1B functions only as a essential catalytic subunits in mel-PRC1 complex Ring1B alone can’t exhist fully E3 ligase activity towards nucleosome The Ring domain of Mel-18 is important for targeting Ring1B to chromatin nullContrary to this article 1)This paper failed to detect H2A ubiquitylation using Mel-18 in complex with Ring1B 2)Ring 1B can’t exhist E3 ubiquitin Ligase alone BACKnullnull