Polycomb group (PcG) protein (PubMed:1898775). PcG proteins act by forming multiprotein complexes, which are required to maintain the transcriptionally repressive state of homeotic genes throughout development (PubMed:1898775, PubMed:11493925, PubMed:11583617). PcG proteins are not required to initiate repression, but to maintain it during later stages of development (PubMed:1898775). Component of the PcG multiprotein PRC1 complex, a complex that acts via chromatin remodeling and modification of histones; it mediates monoubiquitination of histone H2A 'Lys-118', rendering chromatin heritably changed in its expressibility (PubMed:11493925, PubMed:11583617). Promotes locus-specific chromatin compaction (PubMed:11493925, PubMed:11583617). Binds to (N(6)-methyladenosine) DNA and thereby might implement repression of specific loci (PubMed:30078725). Component of PRC1 complex, which contains many PcG proteins like Pc, ph, Scm, Psc, Sce and also chromatin-remodeling proteins such as histone deacetylases. This complex is distinct from the Esc/E(z) complex, at least composed of esc, E(z), Su(z)12, HDAC1/Rpd3 and Caf1-55. The 2 complexes however cooperate and interact together during the first 3 hours of development to establish PcG silencing (PubMed:11493925, PubMed:11583617). Interacts with stx; the interaction targets Pc for ubiquitin-independent proteasomal degradation (PubMed:27326929). Interacts with Nup93-1 (PubMed:31784359). Required during the entire larval period for normal adult development. It is found in almost all cells and tissues throughout gastrulation and organogenesis though at a much lower level than in early syncytial stages.