抄録
In order to elucidate the structure and function of the mitochondrial genome from comparative aspects, the author cloned the entire sequence (17.6 Kb) of the mitochondrial genome of Rana catesbeiana and determined the nucleotide sequences of the URF2 gene and of its flanking genes. The results obtained in the present study are as follows:
1) The Rana catesbeiana URF2 gene contains 1, 033 bases, and, as deduced from its nucleotide sequence, the URF2 protein consists of 344 amino acids with a molecular weight of 37, 561.
2) The URF2 gene is flanked on the 5' side by the tRNA genes for isoleucine, glutamine and methionine and on the 3' side by those for tryptophan and alanine. These genes are identical in their organization to those in the mammalian and Xenopus laevis mitochondrial genomes.
3) A comparison of the putative amino acid sequences of the URF2 proteins of different animal species reveals that six regions in the sequence are well conserved during evolution, suggesting that some of these conserved sequences are crucial for biological activity of the URF2 protein.
4) The nucleotide sequences of the five tRNA genes, tRNAIle, tRNAGGln, tRNAMet, tRNATTrp and tRNAAla exhibit homologies between 55-85% with the mammalian and Xenopus laevis counterparts.
