Review Volume 3, Issue 6 pp 565—575

Figure 4. BMI-1 and Ezh2: Effects on transcription. (A) The Ezh2 (Enhancer of zeste homologue 2) component of the PRC2 (Polycomb repressor complex 2) complex methylates lysine (K) 27 of histone H3 (H3K27). This methylation process recruits the PRC1 (Polycomb repressor complex 1) complex. (B) The Ring1A and Ring1B components of this complex ubiquitylate H2AK119. This ubiquitylation causes transcriptional repression, for example at the Ink4a/Arf locus. In addition to Ezh2, the PRC2 complex contains EED (embryonic ectoderm development) and Suz12 (suppressor of zeste homologue 12). The PRC1 complex contains BMI-1, Ring 1A, Ring 1B, PH1 (Polycomb homologue 1), and PH1 (Polyhomeotic homologue 1). Adapted from [77].