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Sequences from a Prokaryotic Genome or the Mouse Dihydrofolate Reductase Gene Can Restore the Import of a Truncated Precursor Protein into Yeast Mitochondria
Alison Baker and Gottfried Schatz
Proceedings of the National Academy of Sciences of the United States of America
Vol. 84, No. 10 (May 15, 1987), pp. 3117-3121
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/29343
Page Count: 5
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Sequences that are capable of restoring mitochondrial targeting to a truncated yeast cytochrome c oxidase subunit IV presequence are encoded within the genome of Escherichia coli and within the gene for a higher eukaryotic cytosolic protein, mouse dihydrofolate reductase. These sequences, which resemble authentic presequences in their overall amino acid composition and degree of hydrophobicity, are rather frequent; >2.7% of clones generated from E. coli DNA and >5% of clones from the dihydrofolate reductase gene were functional in our screening system. These results suggest that, during evolution, mitochondrial precursor proteins could arise as a result of DNA rearrangements that place potential mitochondrial presequences at the amino terminus of existing open reading frames. Primitive eukaryotic cells may have used this mechanism to target proteins to their endosymbiotic protomitochondria.
Proceedings of the National Academy of Sciences of the United States of America © 1987 National Academy of Sciences