Polycomb group (PcG) protein. Component of the prc2/eed-ezh2 complex, which methylates 'Lys-9' and 'Lys-27' of histone H3, leading to transcriptional repression of the affected target gene (By similarity). Component of the prc2/eed-ezh2 complex. May interact with ezh2, hdac1, taf9 and yy1. Belongs to the WD repeat ESC family.