Practice question

Mitochondrial protein synthesis translating thirteen highly hydrophobic inner membrane subunits of oxidative phosphorylation complexes relies on 55S mitochondrial ribosome in mammals. This ribosome composed of 28S small and 39S large subunits is tethered to inner membrane near OXA1L translocase enabling co-translational insertion of nascent chains. Translation uses nucleus-encoded mitochondrial initiation factors mtIF2, mtIF3, elongation factors mtEFTu, mtEFG1, termination factor mtRF1a, distinct from cytosolic 80S machinery, sensitive to antibiotics, and regulated by mitochondrial tRNA modifications and membrane potential coupling. This refined regulation supports accurate ribosomal assembly, quality control and translational fidelity under diverse physiological conditions and growth states.