Stereo views highlighting the regions interacting across the dimeric and tetrameric interface. The dimeric interfaces are between dimers AB and CD, and the tetrameric interfacebetween dimers AC et BD. Residues involved in ionic interactions at the A/B dimer interface are shown in red or blue spheres (for acidic or basic residues, respectively). Glu226 and Arg230, which form a salt bridge involved in the tetrameric assembly are shown in pink and cyan spheres, respectively. Inter-monomer disulfide bridges between cysteines 196 and 233 in PaTrmI are shown in yellow. A MtTrmI, B TtTrmI, C TmTrmI, D AaTrmI, E PaTrmI.