SET domain (including pre-SET and post-SET domains) found in SET domain bifurcated 1 (SETDB1) and 2 (SETDB2), suppressor of variegation 3-9 homologs, SUV39H1 and SUV39H2, euchromatic histone-lysine N-methyltransferase EHMT1 and EHMT2, and similar proteins.
The family includes SET domain bifurcated 1 (SETDB1) and 2 (SETDB2), suppressor of variegation 3-9 homologs, SUV39H1 and SUV39H2, euchromatic histone-lysine N-methyltransferase EHMT1 and EHMT2. SETDB1 (EC 2.1.1.43; also termed ERG-associated protein with SET domain (ESET), histone H3-K9 methyltransferase 4, H3-K9-HMTase 4, or lysine N-methyltransferase 1E (KMT1E)) acts as a histone-lysine N-methyltransferase that specifically trimethylates 'Lys-9' of histone H3 (H3K9me3). It mainly functions in euchromatin regions, thereby playing a central role in the silencing of euchromatic genes. SETDB2 (EC 2.1.1.43; also termed chronic lymphocytic leukemia deletion region gene 8 protein (CLLD8), or lysine N-methyltransferase 1F (KMT1F)) acts as a histone-lysine N-methyltransferase that specifically trimethylates 'Lys-9' of histone H3 (H3K9me3). It is involved in left-right axis specification in early development and mitosis. SUV39H1 (also termed histone H3-K9 methyltransferase 1, H3-K9-HMTase 1, lysine N-methyltransferase 1A, KMT1A, position-effect variegation 3-9 homolog, SUV39H, or Su(var)3-9 homolog 1) and SUV39H2 (also termed histone H3-K9 methyltransferase 2, H3-K9-HMTase 2, lysine N-methyltransferase 1B, KMT1B, or Su(var)3-9 homolog 2), both act as histone-lysine N-methyltransferases that specifically trimethylate 'Lys-9' of histone H3 (H3K9me3) using monomethylated H3 'Lys-9' as substrate. They mainly function in heterochromatin regions, thereby playing central roles in the establishment of constitutive heterochromatin at pericentric and telomere regions. EHMT1 (also termed Eu-HMTase1, G9a-like protein 1, GLP, GLP1, histone H3-K9 methyltransferase 5, H3-K9-HMTase 5, lysine N-methyltransferase 1D, or KMT1D) and EHMT2 (also termed Eu-HMTase2, HLA-B-associated transcript 8, histone H3-K9 methyltransferase 3, H3-K9-HMTase 3, lysine N-methyltransferase 1C, KMT1C, or protein G9a), both act as histone-lysine N-methyltransferases that specifically mono- and dimethylate 'Lys-9' of histone H3 (H3K9me1 and H3K9me2, respectively) in euchromatin. This family also includes the pre-SET domain, which is found in a number of histone methyltransferases (HMTase), N-terminal to the SET domain. Pre-SET domain is a zinc binding motif which contains 9 conserved cysteines that coordinate three zinc ions. It is thought that this region plays a structural role in stabilizing SET domains. Most family members, except for Arabidopsis thaliana SUVH9, contain a post-SET domain which harbors a zinc-binding site.
Jiyao W et al.(2023). "The conserved domain database in 2023.",