InterPro domain: IPR004541

Translation elongation factors are responsible for two main processes during protein synthesis on the ribosome [ 1 , 2 , 3 ]. EF1A (or EF-Tu) is responsible for the selection and binding of the cognate aminoacyl-tRNA to the A-site (acceptor site) of the ribosome. EF2 (or EF-G) is responsible for the translocation of the peptidyl-tRNA from the A-site to the P-site (peptidyl-tRNA site) of the ribosome, thereby freeing the A-site for the next aminoacyl-tRNA to bind. Elongation factors are responsible for achieving accuracy of translation and both EF1A and EF2 are remarkably conserved throughout evolution.

EF1A (also known as EF-1alpha or EF-Tu) is a G-protein. It forms a ternary complex of EF1A-GTP-aminoacyltRNA. The binding of aminoacyl-tRNA stimulates GTP hydrolysis by EF1A, causing a conformational change in EF1A that causes EF1A-GDP to detach from the ribosome, leaving the aminoacyl-tRNA attached at the A-site. Only the cognate aminoacyl-tRNA can induce the required conformational change in EF1A through its tight anticodon-codon binding [ 4 , 5 ]. EF1A-GDP is returned to its active state, EF1A-GTP, through the action of another elongation factor, EF1B (also known as EF-Ts or EF-1beta/gamma/delta).

This entry represents EF1A (or EF-Tu) proteins found primarily in bacteria, mitochondria and chloroplasts. Eukaryotic and archaeal EF1A ( IPR004539 ) are excluded from this entry. When bound to GTP, EF-Tu can form a complex with any (correctly) aminoacylated tRNA except those for initiation and for selenocysteine, in which case EF-Tu is replaced by other factors [ 6 ].

1. Structural studies of eukaryotic elongation factors. Cold Spring Harb. Symp. Quant. Biol. 66, 425-37
2. Elongation factors on the ribosome. Curr. Opin. Struct. Biol. 15, 349-54
3. Elongation factors in protein biosynthesis. Trends Biochem. Sci. 28, 434-41
4. Recognition and selection of tRNA in translation. FEBS Lett. 579, 938-42
5. Mechanisms of EF-Tu, a pioneer GTPase. Prog. Nucleic Acid Res. Mol. Biol. 71, 513-51
6. How can elongation factors EF-G and EF-Tu discriminate the functional state of the ribosome using the same binding site? FEBS Lett. 579, 5439-42