G9a (BAT8, NG36) is a major histone methyltransferase that acts by adding a methyl group to the Lys9 amino acid on histone H3 proteins. Methylation of Lys9 on histone H3 is important for the regulation of the expression of crucial genes during embryogenesis. Methylation of Lys9 may also play a role in tumorigenesis, since deregulation of histone H3 Lys9 methylation in G9a-deficient cells induces the expression of Mage-2a, a tumor-specific protein whose function is unknown. The 165 kDa G9a protein has an unusual structure, containing 24 contiguous glutamate residues in the N-terminus and 6 contiguous copies of a 33-amino acid ankyrin repeat in the C-terminus. The presence of the ankyrin repeats suggest that G9a may be involved in intracellular protein-protein interactions. G9a is expressed in monocytic, macrophage, hepatocyte, T-cell, B-cell, epithelial, and promyelocytic cell lines.Synonyms: C6orf30, EHMT2, Euchromatic histone-lysine N-methyltransferase 2, H3 lysine-9 specific 3, H3-K9-HMTase 3, HLA-B-associated transcript 8, Histone H3-K9 methyltransferase 3, Histone-lysine N-methyltransferase, KMT1C, Lysine N-methyltransferase 1C, NG36, Protein G9A