Figure 2. Interplay of mitochondrial and nuclear genes in the biogenesis of the respiratory chain.
Mitochondrial (mt) DNA encodes 13 structural subunits of the respiratory chain complexes (red ovals) as well as two ribosomal (r)RNAs and 22 transfer (t)RNAs that are required for mitochondrial protein synthesis. Nuclear (n)DNA encodes all the other structural subunits of the respiratory chain complexes, cytochrome c, assembly factors, the enzymes required for coenzyme Q (CoQ) biosynthesis and proteins involved in mtDNA replication and maintenance and in mitochondrial protein synthesis.