The Drosophila gene Polycomb (Pc) encodes a transcriptional repressor required for the segment-specific repression of homeotic selector genes by promoting locus-specific chromatin compaction. Pc may be involved in the stable transmission of a determined state by its effects on chromatin structure. It contains one chromo domain and interacts genetically with ph-p, Antp, E(Pc), Pcl, Asx, and many other genes. Similar sequences have been identified in African clawed frog, Caenorhabditis elegans, Homo sapiens, and Mus musculus. (from SWISS-PROT P26017, FlyBase 0003042, and NCI) [ ]