| Project/Area Number |
13480207
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Functional biochemistry
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| Research Institution | Nagoya University |
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Principal Investigator |
ENDO Toshiya Nagoya University, Grad.School of Science, Professor, 大学院・理学研究科, 教授 (70152014)
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| Co-Investigator(Kenkyū-buntansha) |
NISHIKAWA Shuh-ichi Nagoya University, Grad.School of Science, Associate Professor, 大学院・理学研究科, 助教授 (10252222)
YOSHIHISA Tohru Nagoya University, R.C.M.S., Associate Professor, 物質科学国際研究センター, 助教授 (60212312)
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| Project Period (FY) |
2001 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥14,800,000 (Direct Cost: ¥14,800,000)
Fiscal Year 2002: ¥5,800,000 (Direct Cost: ¥5,800,000)
Fiscal Year 2001: ¥9,000,000 (Direct Cost: ¥9,000,000)
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| Keywords | mitochondria / translocation across the membranes / yeast / protein flux / proteome / トランスローケータ / 膜透過 / プロテインフラックス / 行き先シグナル / プレ配列 |
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| Research Abstract |
Most mitochondrial proteins are synthesized as precursor proteins in the cytosol and imported into mitochondria with the aid of protein translocation machineries in the outer and the inner membranes called the TOM complex and the TIM complex, respectively. In the present study, we analyzed the mechanisms of the control and regulation of the protein flux into mitochondria.
Based on the results of the site-specific photocrosslinking of the translocation intermediate, we have identified Tim50, a new component of the yeast TIM23 import machinery, which mediates translocation of presequence-containing proteins across the mitochondrial inner membrane. Tim50 is anchored to the inner mitochondrial membrane, exposing the C-terminal domain to the intermembrane space. Tim50 interacts with the N-terminal intermembrane space domain of Tim23. Functional defects of Tim50 either by depletion of the protein or addition of anti-Tim50 antibodies block the protein translocation across the inner membrane. A translocation intermediate accumulated at the TOM complex is crosslinked to Tim50. We suggest that Tim50, in cooperation with Tim23, facilitates transfer of the translocating protein from the TOM complex to the TIM23 complex.
We took a proteome-wide approach of mitochondrial protein import in vitro to find a set of substrate proteins for recognition by Tom70. Translation products of total yeast RNA were imported into isolated wild-type mitochondria and those without Tom70. Comparison of the imported proteins on 2D-electrophoresis gels between wild-type and Δtom70 mitochondria allowed us to identify proteins affected by deletion of Tom70 systematically.
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