Figure 10. Proposed models for the regulation of PcG target gene expression-mediated by BmPho and BmScm.

In this study, we envision that BmPho and BmScm regulate two classes of PcG targets. One class is based on the classic PcG system (Top), and the other one is attributed to the complex itself (Bottom). In the top panel, the DNA-binding protein BmPho associated with BmScm recognizes Polycomb response elements (PRE) and recruits other PRC2 and PRC1 complexes. PRC2 catalyzes the H3K27me3 mark and spreads out bilaterally, finally, resulting in a condensed chromatic status. In the bottom panel, the complex of BmPho and BmScm binds to PRE in the target gene, and subsequently forms the repeated units probably through homodimer and/or heterodimer themselves. Further details are shown in the text.