InterPro domain: IPR035654

Elongation factor 4, also known as ribosomal back-translocase LepA, is required for accurate and efficient protein synthesis under certain stress conditions. Its function is not clear. However, it may act as a fidelity factor of the translation reaction, by catalysing a one-codon backward translocation of tRNAs on improperly translocated ribosomes. Back-translocation proceeds from a post-translocation (POST) complex to a pre-translocation (PRE) complex, thus giving elongation factor G a second chance to translocate the tRNAs correctly [ 1 , 2 ]. Elongation factor 4 binds to ribosomes in a GTP-dependent manner. The eukaryotic homologue is known as GUF1 and promotes protein synthesis in chloroplasts and mitochondria [ 3 ].

EF4 has six domains, of which four (I, II, III, and V) are homologous to corresponding domains in EF-G [ 4 , 5 , 6 ]. This entry represents domain IV of EF4, homologous to domain V of EF-G.

1. The highly conserved LepA is a ribosomal elongation factor that back-translocates the ribosome. Cell 127, 721-33
2. Interrupted catalysis: the EF4 (LepA) effect on back-translocation. J. Mol. Biol. 396, 1043-52
3. The membrane-bound GTPase Guf1 promotes mitochondrial protein synthesis under suboptimal conditions. J. Biol. Chem. 283, 17139-46
4. The structure of LepA, the ribosomal back translocase. Proc. Natl. Acad. Sci. U.S.A. 105, 4673-8
5. Crystal structure of elongation factor 4 bound to a clockwise ratcheted ribosome. Science 345, 684-7
6. Taking a Step Back from Back-Translocation: an Integrative View of LepA/EF4's Cellular Function. Mol. Cell. Biol. 37