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Elongation Factor G-like domain IV. This family includes the translational elongation factor termed EF-2 (for Archaea and Eukarya) and EF-G (for Bacteria), ribosomal protection proteins that mediate tetracycline resistance and, an evolutionarily conserved U5 snRNP-specific protein (U5-116kD). In complex with GTP, EF-G/EF-2 promotes the translocation step of translation. During translocation the peptidyl-tRNA is moved from the A site to the P site of the small subunit of ribosome and the mRNA is shifted one codon relative to the ribosome. It has been shown that EF-G/EF-2_IV domain mimics the shape of anticodon arm of the tRNA in the structurally homologous ternary complex of Petra, EF-Tu (another transcriptional elongation factor) and GTP analog. The tip portion of this domain is found in a position that overlaps the anticodon arm of the A-site tRNA, implying that EF-G/EF-2 displaces the A-site tRNA to the P-site by physical interaction with the anticodon arm.
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