Phylogenetic analysis of the START-domain proteins in Arabidopsis. A neighbor-joining phylogenetic tree was constructed based on the Poisson correction model and complete deletion algorithm (bootstrapped 2,000 replicates). (a) START domains from 35 Arabidopsis START-containing proteins are divided into seven subfamilies. The structure and domain organization for each protein or protein subfamily is shown on the right, with START domains in red and other domains abbreviated as in Figure 1. HD, yellow; PH, purple; ZIP, blue; ZLZ, green; DUF1336, black. Sizes of the corresponding proteins in amino acids (aa) are indicated to the right or below each representation. (b) Phylogenetic comparison of the 35 START proteins from Arabidopsis (black lettering) and the 29 from rice (green boxes). Most Arabidopsis START domains appear to be conserved in rice, and several groupings are likely to reflect orthologous relationships.