mtEF-G2 domain IV. This subfamily is a part the of mitochondrial transcriptional elongation factor, mtEF-G2. Mitochondrial translation is crucial for maintaining mitochondrial function and mutations in this system lead to a breakdown in the respiratory chain-oxidative phosphorylation system and to impaired maintenance of mitochondrial DNA. In complex with GTP, EF-G 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.