Figure 3. Schematic representation for trasmission of epigenetic signatures at PREs. The scheme shows a PcG bound bivalent domain. In G₁ phase minimal amounts of PcG complexes and H3K27me3 and H3K9me3 marks, sufficient for transcriptional repression, are present at PREs. Low levels H3K4me3 mark are also present. During the early S phase PcG complexes are uploaded on their targets and all repressive and active histone marks are enriched. After PREs replication the redistribution on daughter strands reinstates epigenetic marks to the previous steady-state.