Polycomb group multiprotein PRC2 complex; PRC2/EED-EZH2 complex; EZH2 histone methyltransferase complex (PcG)

^[1]^[2]^[3]^[4]

Function

distinct from PRC1 complex
maintenance of transcriptionally repressive state of genes throughout development
acts via chromatin remodeling & modification of histones, rendering chromatin heritably changed in its expressibility
able to mono-, di- & trimethylate Lys-27 of histone H3
minimum components required for methyltransferase activity of the PRC2/EED-EZH2 complex are EED, EZH2 & SUZ12
compacts chromatin in the absence of the methyltransferase cofactor S-adenosyl-L-methionine (SAM
the PRC2 complex may also interact with DNMT1, DNMT3A, DNMT3B & PHF1 via the EZH2 subunit & with SIRT1 via the SUZ12 subunit
may associate with HDAC1
recruiting platform for DNA methyltransferases, thereby linking two epigenetic repression systems (putative)
genes repressed by the PRC2/EED-EZH2 complex include HOXC8, HOXA9, MYT1, CDKN2A & retinoic acid genes

two variants of the PRC2 complex have been described, termed PRC3 & PRC4
each of the three complexes may include a different complement of EED isoforms, although the precise sequences of the isoforms in each complex have not been determined
the PRC2 & PRC4 complexes may also methylate Lys-26 of histone H1 in addition to Lys-27 of histone H3

↑ UniProt http://www.uniprot.org/uniprot/Q15022.html
↑ Kuzmichev A et al Different EZH2-containing complexes target methylation of histone H1 or nucleosomal histone H3. Mol Cell. 2004 Apr 23;14(2):183-93. PMID: https://www.ncbi.nlm.nih.gov/pubmed/15099518
↑ Kuzmichev A et al Composition and histone substrates of polycomb repressive group complexes change during cellular differentiation. Proc Natl Acad Sci U S A. 2005 Feb 8;102(6):1859-64. PMID: https://www.ncbi.nlm.nih.gov/pubmed/15684044
↑ Martin C et al Substrate preferences of the EZH2 histone methyltransferase complex. J Biol Chem. 2006 Mar 31;281(13):8365-70 PMID: https://www.ncbi.nlm.nih.gov/pubmed/16431907