Domain II of bacterial elongation factor G and C-terminal domain of mitochondrial Elongation factors G1 and G2
This family represents the domain II of bacterial Elongation factor G (EF-G)and mitochondrial Elongation factors G1 (mtEFG1) and G2 (mtEFG2). During the process of peptide synthesis and tRNA site changes, the ribosome is moved along the mRNA a distance equal to one codon with the addition of each amino acid. In bacteria this translocation step is catalyzed by EF-G_GTP, which is hydrolyzed to provide the required energy. Thus, this action releases the uncharged tRNA from the P site and transfers the newly formed peptidyl-tRNA from the A site to the P site. Eukaryotic cells harbor 2 protein synthesis systems: one localized in the cytoplasm, the other in the mitochondria. Most factors regulating mitochondrial protein synthesis are encoded by nuclear genes, translated in the cytoplasm, and then transported to the mitochondria. The eukaryotic system of elongation factor (EF) components is more complex than that in prokaryotes, with both cytoplasmic and mitochondrial elongation factors and multiple isoforms being expressed in certain species. mtEFG1 and mtEFG2 show significant homology to bacterial EF-Gs. Mutants in yeast mtEFG1 have impaired mitochondrial protein synthesis, respiratory defects and a tendency to lose mitochondrial DNA. No clear phenotype has been found for mutants in the yeast homolog of mtEFG2, MEF2.
Jiyao W et al.(2023). "The conserved domain database in 2023.",