FIG 4 .

Structures of homologs to cytokinin receptors identified in early diverging fungi. (A) Diversity of structures found in various early diverging fungi. The structures of several previously characterized plant cytokinin receptors (23) and other CHASE domain-containing HHKs (which had not been demonstrated to date to act as cytokinin receptors) from Synechocystis sp. (Cyanobacteria) and Dictyostelium discoideum (Amoebae) are also provided. (B) Alignment of CHASE domains from homologs to cytokinin receptors identified in early diverging fungi, along with others from plant cytokinin receptors. The Dictyostelium and Synechocystis sequences were not included in this analysis because their subgroup was not supported by a high bootstrap value. Interruptions of the alignments are indicated by pink rectangles, and essential residues reported to be involved in cytokinin perception in A. thaliana AtAHK4 are indicated with red arrows (previously compiled in reference 23).