The Era (E. coli Ras-like protein)-like family includes several distinct subfamilies (TrmE/ThdF, FeoB, YihA (EngB), Era, and EngA/YfgK) that generally show sequence conservation in the region between the Walker A and B motifs (G1 and G3 box motifs), to the exclusion of other GTPases. TrmE is ubiquitous in bacteria and is a widespread mitochondrial protein in eukaryotes, but is absent from archaea. The yeast member of TrmE family, MSS1, is involved in mitochondrial translation; bacterial members are often present in translation-related operons. FeoB represents an unusual adaptation of GTPases for high-affinity iron (II) transport. YihA (EngB) family of GTPases is typified by the E. coli YihA, which is an essential protein involved in cell division control. Era is characterized by a distinct derivative of the KH domain (the pseudo-KH domain) which is located C-terminal to the GTPase domain. EngA and its orthologs are composed of two GTPase domains and, since the sequences of the two domains are more similar to each other than to other GTPases, it is likely that an ancient gene duplication, rather than a fusion of evolutionarily distinct GTPases, gave rise to this family.