| Modification Notes |
In Drosophila melanogaster, segment identity is determined by specific expression of homeotic genes (Hox). The Hox expression pattern is first initiated by gap and pair-rule genes and subsequently maintained by genes of the Polycomb-group (Pc-G) and the trithorax-group (trx-G). E(z), or enhancer of zeste, is a Drosophila Polycomb-group transcriptional repressor and one of the founding members of the family of SET-domain-containing proteins. Several SET-domain proteins possess intrinsic histone methyltransferase (HMT) activity. E(z) binds directly to ESC (extra sex combs), another PcG protein, and is present in Drosophila early embryos with ESC in a complex that includes ESC and is recruited to Polycomb response elements. |