ATRX, Dnmt3 and Dnmt3l PHD-like zinc finger domain (ADDz)
The ADDz zinc finger domain is present in the chromatin-associated proteins cytosine-5-methyltransferase 3 (Dnmt3) and ATRX, a SNF2 type transcription factor protein. The Dnmt3 family includes two active DNA methyltransferases, Dnmt3a and -3b, and one regulatory factor Dnmt3l. DNA methylation is an important epigenetic mechanism involved in diverse biological processes such as embryonic development, gene expression, and genomic imprinting. The ADDz domain is a PHD-like zinc finger motif that contains two parts, a C2-C2 and a PHD-like zinc finger. PHD zinc finger domains have been identified in more than 40 proteins that are mainly involved in chromatin mediated transcriptional control; the classical PHD zinc finger has a C4-H-C3 motif that spans about 50-80 amino acids. In ADDz, the conserved histidine residue of the PHD finger is replaced by a cysteine, and an additional zinc finger C2-C2 like motif is located about twenty residues upstream of the C4-C-C3 motif.
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