功能 |
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. In the PRC1 complex, it is required to stimulate the E3 ubiquitin-protein ligase activity of RNF2/RING2.
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總結(jié) |
The polycomb?group (PcG) of proteins?contributes to the maintenance of cell?identity, stem?cell?self-?renewal, cell cycle regulation, and oncogenesis by maintaining the silenced state of genes that promote?cell?lineage specification, cell death, and cell cycle?arrest. PcG proteins exist in two complexes that cooperate to maintain?long term?gene silencing through epigenetic chromatin?modifications. The first complex, EED?EZH2, is recruited to genes by DNA?binding transcription factors and methylates histone H3 on Lys27. This histone methyl?transferase activity requires the Ezh2, Eed, and Suz12 subunits of the complex. Histone H3 methylation at Lys27 facilitates the recruitment of the second complex, PRC1, which ubiquitinylates histone H2A on Lys119. Bmi1 is a component of the PRC1 complex, which together with Ring1 strongly enhances the E3?ubiquitin?ligase activity of the Ring2 catalytic subunit. Bmi1?plays an important role?in?the regulation of cell?proliferation and senescence through repression of the p16 INK4A?and p19 ARF genes and is required for maintenance of adult hematopoietic and neural?stem cells.
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