A comparison of mitochondrial tRNAs in five vertebrates.

Sequences of several vertebrate mitochondrial tRNAs were aligned and compared. The comparisons were made in pairs of the tRNAs for an identical amino acid. There are 22 genes for different tRNAs in each vertebrate mitochondrial DNA. The closet similarities were between rat and mouse, the next were between mammals, and the widest difference was between human or rat and Xenopus laevis. However, there were very wide variations between different amino acids in each set of comparisons. The time lapse for each percent of difference greatly increased with evolutionary separation. Most of the nucleotide substitutions appeared to be neutral in character.