has participant hydron L-lysinium residue S-adenosyl-L-homocysteine zwitterion S-adenosyl-L-methionine zwitterion N(6),N(6),N(6)-trimethyl-L-lysine residue histone H3K27 methyltransferase activity histone H3K27 trimethyltransferase activity https://github.com/geneontology/go-ontology/issues/22588 https://github.com/geneontology/go-ontology/issues/30578 RHEA:60292 histone H3K27 mono/di/trimethylase activity histone H3-K27 trimethylation molecular_function GO:0140951 histone lysine N-trimethyltransferase activity (H3-K27 specific) 2022-11-01T13:26:01Z histone H3-K27 trimethylase activity EC:2.1.1.356 histone H3K27 trimethylation Catalysis of the reaction: L-lysyl27-[histone H3] + 3 S-adenosyl-L-methionine = 3 H+ + N6,N6,N6-trimethyl-L-lysyl27-[histone H3] + 3 S-adenosyl-L-homocysteine. This reaction is the successive addition of three methyl groups to the unmethylated lysine residue at position 27 of histone H3, producing histone H3K27me3. pg histone H3K27 trimethylase activity Comment: Note that the residue position corresponds to the canonical human H3 histone (UniProtKB:P84243); this residue is conserved across all eukaryotes. Residue 1 is the first residue following removal of the initiating Methionine (Met). Note that each histone is encoded by multiple genes, and sequences may vary across different genes within an organism.