A different genetic code in human mitochondria

Abstract
Comparison of the human mitochondrial DNA sequence of the cytochrome oxidase subunit II gene and the sequence of the corresponding beef heart protein shows that UGA is used as a tryptophan codon and not as a termination codon and suggests that AUA amy be a methionine and not an isoleucine codon. The cytochrome oxidase II gene is contiguous at its 5'' end with a tRNAAsp gene and there are only 25 bases at its 3'' end before a tRNALys gene. These tRNAs are different from all other known tRNA sequences.