chromodomain of polycomb and chromobox family proteins
CHRomatin Organization Modifier (chromo) domain of Polycomb and Polycomb-group (PcG) chromobox (CBX) family proteins such as CBX2, CBX4, CBX6, CBX7, and CBX8. These CBX proteins are components of the PcG repressive complex PRC1, one of the two classes of PRCs. PcG proteins form large multiprotein complexes (PcG bodies) which are involved in the stable repression of genes involved in development, signaling or cancer via chromatin-based epigenetic modifications. Mammalian PRC1 includes canonical (cPRC1) and non-canonical complexes; cPRC1, contains four core subunits including one CBX protein (CBX2, CBX4, and CBX6-CBX8) that binds H3K27me3. CBX family members have different affinity for H3K27me3, with CBX7 having the highest binding capability. The human CBX proteins show distinct nuclear localizations and contribute differently to transcriptional repression. Some CBX proteins of the PRC1 complex have been implicated in transcriptional activation as well as in PRC1-independent roles in embryonic stem cells and in somatic cells.
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