Sequence alignment and crystal structures of phosphoserine phosphatase SerB from Vibrio cholera (bottom sequence, gray ribbons, PDB ID 3N28, Patskovsky, Y. et al. unpublished) and Mycobacterium avium solved by iodide ion SAD (top sequence, green ribbons, PDB ID 3P96). For simplicity, only one monomer of the biological dimer is shown in each case. Domains 1, 2, and 3 of Ma SerB correspond to residues 1–85, 97–175, and 182–400, respectively