Domain II of mitochondrial elongation factor G1-like proteins found in eukaryotes
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. Eukaryotic EF-2 operates in the cytosolic protein synthesis machinery of eukaryotes, EF-Gs in protein synthesis in bacteria. Eukaryotic mtEFG1 proteins 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. There are two forms of mtEFG present in mammals (designated mtEFG1s and mtEFG2s); mtEFG2s are not present in this group.
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