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. Author manuscript; available in PMC: 2021 May 1.
Published in final edited form as: Bioessays. 2020 Mar 20;42(5):e1900192. doi: 10.1002/bies.201900192

Fig. 1. Schematic representation of PRC1 complexes.

Fig. 1.

PRC1 complexes are divided into two main groups, canonical PRC1 (cPRC1) complexes and non-canonical PRC1 (ncPRC1) complexes. Both groups contain core subunits, present in all sub-complexes of a subtype, which together with other accessory proteins define the complete composition of each sub-complex. (A) At their core, cPRC1 complexes each contain the E3-ligase subunit RING1A or RING1B that catalyzes the monoubiquitination of histone H2AK119, together with either PCGF2 or PCGF4. The additions of a CBX protein and PHC protein define a cPRC1 complex that can recognize the PRC2-mediated H3K27me3 histone mark. (B) In ncPRC1 complexes, CBX and PHC proteins are replaced by RYBP or YAF2 proteins, and the core complex is not restricted to PCGF2/4 and can be formed with any other PCGF1–6 protein.