The structure of the active HotDog domain dimer. (A) A ribbon representation of the Escherichia coli FabA dimer (PDB code: 1MKB), viewed along the dyad axis. Each 171-residue subunit contains a Hotdog fold/ domain, consisting of a seven-stranded antiparallel b-sheet 'bun', coloured magenta and green, and a five-turn a-helical 'sausage' coloured blue and purple in the respective subunits. The Hotdog fold is best observed in Figure B. There are two independent active sites located between the dimers, the active site residues of His70 from one subunit and Asp84 from the other subunit, represented as a ball-and-stick model with CPK colouring (carbon, black; hydrogen, white; oxygen, red; nitrogen, blue), constitute the potential reactive protein groups in the active sites . (B) A view of FabA rotated 90° along the dyad axis. The figures were generated with MOLSCRIPT  and rendered with RASTER3D .