Alignment of methylthioribose-1-phosphate isomerases. Conserved residues are indicated in red, while conservative replacements are indicated in blue. Organisms are labelled as in Figure 2, with a few additional organisms: AQUAE Aquifex aeoliqus; ARATH Arabidopsis thalina and MUSMU Mus musculus. The sequence of mouse initiation factor eIF-2B (alpha subunit) is shown for comparison. The § symbol at the beginning and the end of the K. aeruginosa sequence corresponds to regions that have not been identified from the ongoing genome programme sequences.