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Ubiquitin modification of many cellular proteins targets them for proteasomal degradation, but in addition can also serve non-proteolytic functions. Over the last years, a significant progress has been made in our understanding of how modification of the substrates of the ubiquitin system is regulated. However, little is known on how the ubiquitin system(More)
Methylation of lysine 27 on histone H3 by the polycomb repressive complex 2 (PRC2) leads to transcriptional repression of genes which are critical to development. PRC2 core complex is composed of the histone methyltransferase EZH2, EED, and SUZ12. Knockdown of any of the PRC2 core subunits results in a concomitant loss of the other subunits which is(More)
The effects of aqueous extracts of Osbeckia octandra whole plant, Melothria maderaspatana whole plant and Phyllanthus debelis leaves on the human immune system were investigated. The extracts showed strong anticomplement effects on both the classical and alternate pathways of the human complement system in vitro. The effects were dose-dependent and most(More)
The polycomb repressive complex (PRC) 1 protein Ring1B is an ubiquitin ligase that modifies nucleosomal histone H2A, a modification which plays a critical role in regulation of gene expression. We have shown that self-ubiquitination of Ring1B generates multiply branched, "noncanonical" polyubiquitin chains that do not target the ligase for degradation, but(More)
The E3 ubiquitin ligase RING1B plays an important role in Polycomb-mediated gene silencing by monoubiquitinating histone H2A. Both the activity and stability of RING1B are controlled by ubiquitination in two distinct manners. Self ubiquitination of RING1B generates K6, K27 and K48-based mixed polyubiquitin chain, and is required for its activity as a(More)
The activity and stability of the E3 ubiquitin ligase RING1B are controlled by the ubiquitin system. Self-ubiquitination of RING1B, generating K6, K27 and K48-based mixed polyubiquitin chains, is a prerequisite for its activity as an E3 ligase for histone H2A. Monoubiquitination of histone H2A is one of the hallmarks of Polycomb-mediated gene silencing. The(More)
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