chromodomain of histone methyltransferase SUV39H1, and similar proteins
CHRomatin Organization Modifier (chromo) domain of human SUV39H1, a histone lysine methyltransferase (HMT) which catalyzes di- and tri-methylation of lysine 9 of histone H3 (H3K9me2/3), leading to heterochromatin formation and gene silencing. H3K9me2/3 represents a specific mark for epigenetic transcriptional repression by recruiting HP1 (CBX1, CBX3, and/or CBX5) proteins to methylated histones. SUV39H1 mainly functions in heterochromatin regions. The human SUV39H1/2, histone H3K9 methyltransferases, are the mammalian homologs of Drosophila Su(var)3-9 and Schizosaccharomyces pombe Clr4. SUV39H1 contains a chromodomain at its N-terminus and a SET domain at its C-terminus. Although the SET domain performs the catalytic activity, the chromodomain of SUV39H1 is essential for the catalytic activity of SUV39H1. A chromodomain is a conserved region of about 50 amino acids, found in a variety of chromosomal proteins, and which appears to play a role in the functional organization of the eukaryotic nucleus. The chromodomain is implicated in the binding, of the proteins in which it is found, to methylated histone tails and maybe RNA. A chromodomain may occur as a single instance, in a tandem arrangement, or followed by a related chromo shadow domain.
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