Multiple sequence alignment of RhAG, RhBG, and RhCG. Using CLUSTALW, a sequence alignment was generated to illustrate the conserved aspartate group in AmtB, RhAG, RhBG, and RhCG. The residue D160 in AmtB (Javelle et al. 2004) and the homologous D177 in RhCG (Marini et al. 2006) have been reported to be critical for NH3 transport. This residue is also conserved in RhAG and RhBG. The WT sequence used for AmtB was Swissprot P69681. GenBank accession numbers for the other proteins were AF031548 (RhAG), AF193807 (RhBG), and AF193809 (RhCG).