Alignment of CTU2-homologs. The CTU2-homologs of Arabidopsis (Arab) [TAIR: At4g35910], potato (Solanum tuberosum; Sola [UniProtKB: M4D5F7]), rice (Oryza sativa; Oryza [UniProtKB: Q2QMW0]), and humans (Homo sapiens; human [UniProtKB: Q2VPK5] were aligned using ClustalW software. Identical positions among the plant proteins or all proteins are indicated in black. Domains largely conserved between human and plant proteins  are framed red. Identical, conserved, and similar positions in the alignment are indicated by asterisks, colons, or single dots, respectively. The PP-loop important for ATP binding is underlined with a bold line.