| Type: | Family | Name: | Histone-lysine N-methyltransferase, EZ |
| Description: | Members of this family are polycomb group (PcG) proteins from plants. They act as the catalytic subunit of some PcG multiprotein complex, which methylates 'Lys-27' of histone H3, leading to transcriptional repression of the affected target genes. These enzymes are also required to regulate floral development by repressing the AGAMOUS homeotic gene in leaves, inflorescence stems and flowers. They regulate the antero-posterior organisation of the endosperm, as well as the division and elongation rates of leaf cells. 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 [, , , , , , , , ].Methyltransferases (EC 2.1.1.-) constitute an important class of enzymes present in every life form. They transfer a methyl group most frequently from S-adenosyl L-methionine (SAM or AdoMet) to a nucleophilic acceptor such as oxygen leading to S-adenosyl-L-homocysteine (AdoHcy) and a methylated molecule [, , ]. All these enzymes have in common a conserved region of about 130 amino acid residues that allow them to bind SAM []. The substrates that are methylated by these enzymes cover virtually every kind of biomolecules ranging from small molecules, to lipids, proteins and nucleic acids [, , ]. Methyltransferase are therefore involved in many essential cellular processes including biosynthesis, signal transduction, protein repair, chromatin regulation and gene silencing [, , ]. More than 230 families of methyltransferases have been described so far, of which more than 220 use SAM as the methyl donor. | Short Name: | Hist-Lys_N-MeTrfase_EZ |
