Figure 3.

The evolution of the different types of MYB TFs. The alternative ‘gain’ or ‘loss’ model explains the origin of the 3R- and 2R-MYB types through the acquisition or deletion of the R1 repeat, respectively. The 4R-MYBs (with four R repeats) and the 1R-MYBs (or MYB-related ones) have evolved from these two types, with the last divided into five classes, all with a single R repeat. The GARP family of TFs is evolutionarily distant from the MYBs, even though its B-domain assumes a three-dimensional structure similar to that of the MYB domain.