This family represents domain IV of archaeal and eukaryotic elongation factor 2 (aeEF-2) and of an evolutionarily conserved U5 snRNP-specific protein. U5 snRNP is a GTP-binding factor closely related to the ribosomal translocase EF-2. In complex with GTP, 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-2_IV domain mimics the shape of anticodon arm of the tRNA in the structurally homologous ternary complex of Phe-tRNA, EF-1 (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-2 displaces the A-site tRNA to the P-site by physical interaction with the anticodon arm.
Jiyao W et al.(2023). "The conserved domain database in 2023.",