Practice question

Following peptide bond formation, ribosomes interconvert between classical and hybrid tRNA states requiring active translocation. Elongation factor G, a conserved five-domain GTPase historically termed translocase, binds the rotated pre-translocation ribosome containing peptidyl-tRNA in A/P and deacylated tRNA in P/E states. GTP hydrolysis and phosphate release drive conformational changes that move mRNA and tRNAs by exactly one codon, with domain IV of EF-G inserting into the A-site to block reversal and maintain frame. Peptidyl-tRNA shifts from A to P and deacylated tRNA from P to E, exposing next codon. EF-Tu and EF-Ts participate earlier in tRNA selection, not translocation steps.