The MYB (myeloblastosis) transcription factor family is present in all eukaryotes. MYB DNA-binding domain, contains ~52 amino acid residues in length and forms a helix-turn-helix fold with three regularly spaced tryptophan residues. Based on the number of adjacent MYB repeats, MYB transcription factors are classified into four major groups, namely 1R-MYB, 2R-MYB, 3R-MYB and 4R-MYB containing one, two, three and four MYB repeats, respectively. In animals, R1R2R3- type MYB domain proteins are predominant, while in plants, the R2R3-type MYB domain proteins are more prevalent.
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