nuclear ubiquitin ligase complex PcG protein complex PRC1 complex cellular_component Polycomb repressive complex 1 A multiprotein complex that mediates monoubiquitination of lysine residues of histone H2A (lysine-118 in Drosophila or lysine-119 in mammals). The complex is required for stable long-term maintenance of transcriptionally repressed states and is involved in chromatin remodeling. In Drosophila the core subunits are Pc (Polycomb), Psc (Posterior sex combs), Ph (Polyhomeotic) and Sce (Sex comb extra). In mammals, which have several orthologs for each of the Drosophila core proteins, a family of distinct PRC1-like complexes seem to exist which contain at least some PcG proteins in mutually exclusive manner. GO:0035102