InterPro domain: IPR035647

EF2 (or EFG) participates in the elongation phase of protein synthesis by promoting the GTP-dependent translocation of the peptidyl tRNA of the nascent protein chain from the A-site (acceptor site) to the P-site (peptidyl tRNA site) of the ribosome. EF2 also has a role after the termination phase of translation, where, together with the ribosomal recycling factor, it facilitates the release of tRNA and mRNA from the ribosome, and the splitting of the ribosome into two subunits [ 1 ]. EF2 is folded into five domains, with domains I and II forming the N-terminal block, domains IV and V forming the C-terminal block, and domain III providing the covalently-linked flexible connection between the two. Domains III and V have the same fold (although they are not completely superimposable and domain III lacks some of the superfamily characteristics), consisting of an alpha/beta sandwich with an antiparallel beta-sheet in a (beta/alpha/beta)x2 topology [ 2 ].

Elongation factor 4 (EF4/LepA) is a highly conserved guanosine triphosphatase translation factor. EF4 has six domains, of which four (I, II, III, and V) are homologous to corresponding domains in EF-G. It differs from EF-G by having a short domain IV, and possessing a conserved C-terminal domain [ 3 , 4 ].

This superfamily represents a domain found in EF2, EF4, as well as in some tetracycline resistance proteins, peptide chain release factors [ 5 ] and in the C-terminal region of the bacterial hypothetical protein, YigZ.

1. Translational elongation factor G: a GTP-driven motor of the ribosome. Essays Biochem. 35, 117-29
2. Structure of a mutant EF-G reveals domain III and possibly the fusidic acid binding site. J. Mol. Biol. 303, 593-603
3. The structure of LepA, the ribosomal back translocase. Proc. Natl. Acad. Sci. U.S.A. 105, 4673-8
4. Crystal structure of elongation factor 4 bound to a clockwise ratcheted ribosome. Science 345, 684-7
5. Conserved motifs in prokaryotic and eukaryotic polypeptide release factors: tRNA-protein mimicry hypothesis. Proc. Natl. Acad. Sci. U.S.A. 93, 5443-8