1987 Fiscal Year Final Research Report Summary
Research on the receptor for the precursors of mitochondrial proteins and the cytosolic factor required for their import
| Project/Area Number |
61480463
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
代謝生物化学
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| Research Institution | Yamagata University School of Medicine, Department of Biochemistry |
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Principal Investigator |
TUBOI Syozo Yamagata University School of Medicine, 医学部, 教授 (70004554)
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| Co-Investigator(Kenkyū-buntansha) |
ONO Hideyu Yamagata University School of Medicine (KAWAZOE,Yosh), 医学部, 助手 (40160915)
YOSHIDA Tadashi Yamagata University school of Medicine, 医学部, 助教授 (10004673)
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| Project Period (FY) |
1986 – 1987
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| Keywords | Mitochondria / Fxtra-peptide / Precursor of Ornithine aminotransferase / Cytosolic factor / Receptor for precursor protein / 蛋白質細胞内局在化機構 |
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| Research Abstract |
The mechanism of import of proteins into mitochondria was studied by using the peptide of the presequence of ornithine aminotransferase (the extra- peptide), which was chemically synthesized and is composed of 34 amino acids. When the extra-peptide was incqbated with isolated mitochondria in the presence or a rabbit reticulocyte lysate at 25 C, it was imported into the mitochondrial matrix and the import depended on the inner membrane potential, but not added ATP. The imports of several precursors of mitochondrial proteins were competitively inhibited by the presence of excess extra-peptide in the reaction system, indicating that the extra-peptide and mitochondrial proteins were. imported by the same machinery.
Import of the extra-peptide was significantly stimulated by addition of a rabbit reticulocyte lysate, and a component of the lysate (the cytosolic factor) stimulating import of the extra-peptide was purified about 20,000 times by successive column chromatographies on DEAE-cellulose and aminopentyl-Sepharose 4B. The binding of the extra-peptide to liposomes composed of egg lecithin and partially purified receptor of the precursor of mitochondrial protein required the cytosolic factor, when the concentration of the peptide was less than 1.5 x 10-8 M, suggesting that the physiological binding of the precursors of mitochondrial proteins to the receptor is dependent on the cytosolic factor. The extra-peptide and the cytosolic factor were shown to form a complex.
From these results, the mechanism of binding of the extra-peptide to the receptor of the mitochondrial outer membrane is suggested to be as follows: the peptide (the precursor of mitochondrial protein) and the cytosolic factor form a complex, and then the complex is recognized by, and bound to the receptor.
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