Component of a Polycomb group (PcG) multiprotein PRC1-like complex, a complex class required to maintain the transcriptionally repressive state of many genes, including Hox genes, throughout development. PcG PRC1 complex acts via chromatin remodeling and modification of histones; it mediates monoubiquitination of histone H2A 'Lys-119', rendering chromatin heritably changed in its expressibility. Component of a PRC1-like complex. Interacts with RING1 RNF2, PCGF1, PCGF2, PCGF3, BMI1, PCGF5 AND PCGF6. Interacts with MLLT3 and histone H3. Interacts with PHC2 (By similarity). The human orthologuous proteins of Drosophila Polycomb group protein Pc, CBX2, CBX4, CBX6, CBX7 and CBX8, show distinct nuclear localizations, contribute differently to transcriptional repression, and appear to be part of distinct PRC1-like protein complexes. The hPRC-H complex purification reported by PubMed:12167701 probably presents a mixture of different complexes.