Suz12 is a Polycomb group (PcG) protein. These proteins form multiprotein complexes, which keep homeotic genes in a transcriptionally repressive state throughout development. PcG proteins are not required to initiate repression, but maintain it during later stages of development. They probably act via the methylation of histones. Suz12 is a component of the PRC2 complex, which is composed of EED, EZH2, SUZ12/JJAZ1, RBBP4 and RBBP7, and methylates ‘Lys-9’ and ‘Lys-27’ of histone H3.