Three separate mitochondrial DNA sequences are contiguous in human genomic DNA.
We isolated from a HeLa genomic library 38 plaques that hybridized to total mitochondrial (mt) DNA isolated from human placenta. One clone (HLmt-17.8) hybridized to a 740 base-pair (12 S ribosomal RNA gene and displacement loop) mtDNA probe and was characterized in more detail. Within its 17.8 x 10(3) base-pair insert a 1.6 x 10(3) base-pair mtDNA fragment was similar to three non-sequential coding genes of human mtDNA, including a part of the 12 S ribosomal RNA (684-971), the cytochrome oxidase I (6553-7302), and two NADH dehydrogenase [ND4L/ND4] (10,606-11,159). The similarity to human mtDNA sequences was 92.0%, 92.3% and 92.4%, respectively, the highest degree of similarity to human mtDNA so far reported. This is also the first report of several adjacent mtDNA-like sequences in cellular chromosomes. The mtDNA-like sequences in HLmt-17.8 was found in the DNAs of human placenta, freshly isolated human leukocytes, foreskin and several human cell lines; but it was not present in other primates or lower organisms. The HLmt-17.8 mtDNA-like region appears to be a pseudogene that transferred into the nucleus in humans more recently than nine million years ago.
Kamimura
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Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas 75235.
Ishii
S
S
Ma
L D
LD
Shay
J W
JW
D001483:Base Sequence; D004272:DNA, Mitochondrial / Q000235:genetics*; D005796:Genes; D015698:Genomic Library; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid
D004272:DNA, Mitochondrial