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 plant in some proteins together with a classic Myb repeat, a type-B ARR proteins domain is also present. ARR –B domain is involved in His?Asp phosphorelay signaling. This kind of response regulator domain and myb domain together appears to be a present only in plants, which belong to the GARP subfamily.
1. C. Martin, J. Paz-Ares, MYB transcription factors in plants. Trends Genet 13, 67 (1997) 2. K. Hosoda, A. Imamura, E. Katoh, T. Hatta, M. Tachiki, H. Yamada, T. Mizuno, T. Yamazaki, Molecular structure of the GARP family of plant Myb-related DNA binding motifs of the Arabidopsis response regulators. Plant Cell 14, 2015 (2002)