Homology modelling of STIV B204, ATV p529 and ATV p618. Reliable homology models for STIV B204, ATV p529 and ATV p618 were generated using the I-TASSER server . (A) STIV B204 (rainbow) and STIV2 B204 (PDB: 4KFU) (grey). The residues that interact with the ligand are shown for STIV2 B204 (inset). (B) ATV p529 (shades of blue) and the AAA+ ATPase p97 (PDB: 3CF1) (shades of black and grey). The p97 domains  are indicated (N: black; D1: dark grey; D2: light grey). The p529 ATPase active N-terminal domain (dark blue) maps to the p97 N- and D1 –domains, and the p529 C-terminal endonuclease active domain (light blue) to the p97 D2-domain. The p97 nucleotide binding site in the D2-domain is highlighted (black circle), and the p529 Walker A and B domains are indicated (red and green, respectively) mapping onto the nucleotide binding site of p97 domain D1. (C) ATV p618 (rainbow) and the AAA+ ATPase RavA (PDB: 3NBX) (grey) . The domain organisation of RavA is indicated, and the active site is highlighted (black circle). The figure was rendered in UCSF Chimera .