Sequence analysis of the Arabidopsis ACR family. (A) Phylogenetic relationships of Arabidopsis ACR proteins and the C-terminal ACT domains of E. coli GlnD. Full-length amino acid sequences of Arabidopsis ACR1 to ACR12 and amino acid residues 708-890 of E. coli GlnD were aligned by ClustalW2 and the neighbor-joining algorithm was used to obtain the phylogenetic tree. (B) Schematic gene structures of Arabidopsis ACR9 to ACR12. Exons are shown as black boxes and introns are indicated as solid lines. (C) Schematic diagram of Arabidopsis ACR9 to ACR12 proteins. The black boxes indicate the ACT domains.