Structures of isolated domains of ATR. (A) Close-up views of the isolated domains of ATR shown in ribbon representations. These domains include the N-HEAT, M-HEAT, FAT, and kinase domain (containing FATC). The ATR monomer (ATR-A conformation) is shown in middle panel with CATR (containing FAT, KD and FATC) and MCATR (containing M-HEAT and CATR) indicated. (B) Two views of C-terminal MCATR, which contains M-HEAT, FAT, KD and FATC. The inter-domain connections are indicated within dashed circles. Regions that binds to the N-lobe insert are indicated.