Direct binding of WD40 repeat of Embryonic Ectoderm Development (EED) in the Polycomb Repressor Complex 2 (PRC2) to the histone H3 tail regulates the H3K27 methyltrasnferase activity of PRC2. The binding activity is required for the methylation of H3K27 over long distance of a Drosophila chromosome from the UBX (Hox gene) promoter to the PBX upstream enhancer region, implying EED initiates propagation of this repressive mark.