Figure 1.

Schematic representation of human mtDNA and basic steps of mtRNA metabolism. MtDNA encodes 7 of the 43 subunits of complex I, 1 of the 11 subunits of complex III, 3 of the 13 subunits of complex IV, 2 subunits of ATP synthases, 2 ribosomal RNAs and 22 transfer RNAs. ND4L/ND4 and ATP8/ATP6 transcripts are bicistronic. Transcription of mtDNA leads to formation of two polycistronic transcripts. During the processing and maturation, individual mRNA, rRNA, and tRNA sequences are released from the primary transcript, mainly by excision of tRNAs by RNase P and ELAC2. The created transcripts undergo diverse following processes that lead to stabilization, translation or degradation. Selected proteins involved in these processes are presented. Created with BioRender.com.