Three-dimensional structure of homeodomains from different groups. (a) Crystal structure of the homeodomain from the mammalian ParaHox protein Pdx1 in complex with DNA  (PDB 2h1kB, visualized with NCBI MMDB  using Cn3D 4.1). (b) Visualization of the homeodomain shown in (a) without DNA, visualized with the Protein Picture Generator  using DINO . (c) Visualization (carried out as in (b)) of the A. thaliana WUS homeodomain. Template search was conducted using HHSearch (identifying 2h1kB) and subsequent homology modeling using the alignment mode as implemented in SWISS-MODEL . Note the two loop extensions (arrowed) in the WOX homeodomain as compared with the animal protein.