Genes containing methionine synthase domains. (A) Members of the MHT superfamily. Proteins were aligned with the first ~350 residues of E. coli metH which contains the MHT domain. (B) mmuM, MHT1 and MHT2 (in red) occur in clusters with transporters mmuP, dppABCD and arcD (in blue) respectively. (C) Members of the CIMS-C-terminal-like family. Proteins were aligned with the C-terminal half of E. coli metE which is the more conserved half. Genes have been collapsed by genus and are indicated by the species abbreviation of one representative member of the genus. The number in parentheses afterwards indicates the number of species which were excluded. Species color-coding is as described in Figure 2. Genes with metboxes are in bold and marked with an asterisk.