Polycomb group (PcG) protein. Catalytic subunit of some PcG multiprotein complex, which methylates 'Lys-27' of histone H3, leading to transcriptional repression of the affected target genes, mainly abscisic acid (ABA) responsive elements (PubMed:30307069). PcG proteins act by forming multiprotein complexes, which are required to maintain the transcriptionally repressive state of homeotic genes throughout development. PcG proteins are not required to initiate repression, but to maintain it during later stages of development (By similarity). L-lysyl(27)-[histone H3] + 3 S-adenosyl-L-methionine = 3 H(+) + N(6),N(6),N(6)-trimethyl-L-lysyl(27)-[histone H3] + 3 S-adenosyl-L-homocysteine Component of the plant homeodomain / polycomb repressive complex 2 (PHD-PRC2) large complex during prolonged cold, composed of core PRC2 components (VRN2, EZA1, FIE and MSI1), and three related PHD finger proteins (VIL1, VIL2 and VIN3) that mediates histone H3 trimethylation on 'Lys-27' H3K27me3. Interacts with TAF13. Interacts with EOL1 (PubMed:28428341). The double mutant clf-50 swn-1 is hypersensitive to abscisic acid (ABA) associated with reduced ABA-responsive genes repression by histone H3 'Lys-27' methylation (H3K27me3). Belongs to the class V-like SAM-binding methyltransferase superfamily. Histone-lysine methyltransferase family. EZ subfamily.