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 (PubMed:12167701, PubMed:15386022, PubMed:19636380, PubMed:21282530). Interacts with CBX4 (PubMed:21282530). Interacts with BMI1, PCGF2, PHC1 and RNF2 (PubMed:9121482, PubMed:9199346, PubMed:12167701). Interacts with CHTOP (By similarity). Interacts with the N-terminal region of the SP1 transcription factor and with MAPKAPK2 (PubMed:10976766, PubMed:15094067). HD1 motif interacts with SAM domain of PHC1. The hPRC-H complex purification reported by PubMed:12167701 probably presents a mixture of different PRC1-like complexes. Extended N-terminus. Extended N-terminus.