The complete sequence of the 16,569-base pair human mitochondrial genome is presented. The genes for the 12S and 16S rRNAs, 22 tRNAs, cytochrome c oxidase subunits I, II and III, ATPase subunit 6, cytochrome b and eight other predicted protein coding genes have been located. The sequence shows extreme economy in that the genes have none or only a few noncoding bases between them, and in many cases the termination codons are not coded in the DNA but are created post-transcriptionally by polyadenylation of the mRNAs.

The nucleotide sequence spanning the ribosomal RNA (rRNA) genes of cloned human mitochondrial DNA reveals an extremely compact genome organization wherein the putative tRNA genes are probably 'butt-jointed' around the two rRNA genes. The sequences of the rRNA genes are significantly homologous in some regions to eukaryotic and prokaryotic sequences, but distinctive; the tRNA genes also have unusual nucleotide sequences. It seems that human mitochondria did not originate from recognizable relatives of present day organisms.

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