1989 Fiscal Year Final Research Report Summary
Mechanism of Translocation of Proteins across Mitochondrial and Microsomal Membranes.
| Project/Area Number |
63480503
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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 | Kyushu University |
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Principal Investigator |
OMURA Tsuneo Kyushu University, Graduate School of Medical Sciences, Department of Molecular Biology, Professor, 大学院・医学系研究科, 教授 (80029933)
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| Project Period (FY) |
1988 – 1989
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| Keywords | Mitochondrial membrane / Microsomal membrane / Protein translocation across membranes |
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| Research Abstract |
1. Mitochondrial targeting signals in the precursor peptides of adrenodoxin and P-450(SCC) were examined, and were found in both cases to be in the 15-20 amino acid residues-long amino terminal portions of the extension peptides.
2.20-25 amino acid residues-long amino terminal portions of the extension peptides of P-450(SCC), P-450(11beta), and adrenodoxin precursors were chemically synthesized, and used in detecting mitochondrial protein components having specific affinity to the synthetic peptides. A few mitochondrial proteins were found to have high affinity to the peptides.
3. Selective adsorption of mitochondrial protein precursors to cardiolipin-containing liposomes was found. This finding suggests some role of cardiolipin in the specific binding of protein precursors to mitochondira.
4. A metal protease which efficiently processed mitochondrial protein precursors to mature forms was purified to homogeneity from rat and bovine liver mito chondria. The purified enzyme was a heterodimer of 2 subunits, whose molecular weights were 52 KD,and 55 KD. Cleavage of adrenodoxin precursor by the purified protease confirmed its endoprotease nature.
5. Structural requirements of the amino terminal signal peptides for co-translational insertion of the peptides into microsomal membrane were examined with a cell-free system. The insertion of the peptides was depend on the hydrophobicity of the hydrophobic stretch in the signal peptides.
6. Structural requirements of stop-transfer sequences for efficient interruption of the translocation of peptides across microsomal membrane were examined.
The hydrophobicity of, the middle portion of stop-transfer sequences had primary importance in the interruption of peptide translocation. Charged amino acid residues following the hydrophobic stretch affected the efficiency of the stop-transfer sequences.
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