| Budget Amount *help |
¥28,000,000 (Direct Cost: ¥28,000,000)
Fiscal Year 1985: ¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 1984: ¥5,000,000 (Direct Cost: ¥5,000,000)
Fiscal Year 1983: ¥20,000,000 (Direct Cost: ¥20,000,000)
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| Research Abstract |
Some microsomal membrane proteins including P-450(PB-1) and P-450(MC-1) were synthesized by the membrane-bound ribosomes of rough endoplasmic reticulum, whereas some others including aldehyde dehydrogenase were synthesized by free ribosomes in the cytoplasm. Microsomal proteins seem to be heterogeneous in the mechanism of their integration into the membrane.
Concerning the biogenesis of mitochondria, an intermembrane space protein sulfite oxidase, two inner membrane proteins P-450(SCC) and P-450(11 <beta> ), and several matrix proteins including adrenodoxin and adrenodoxin reductase were all found to be synthesized as larger precursors by free ribosomes. The precursors were imported in vitro into the inside of mitochondria, and their extension peptides were cleaved by metalloproteases in mitochondria. Judging from the substrate specificity and the intra-mitochondrial distribution, a few different metalloproteases seem to be participating in the processing of the precursors of mitochondrial enzymes. A soluble matrix protease processing adrenodoxin was partially purified, and its properties were studied. The cDNAs of P-450(SCC) and adrenodoxin were cloned, and the amino acid sequences of the extension peptides were elucidated. Model peptides resembling some parts of the extension peptides were synthesized, and were found to inhibit the import of the precursors into mitochondria. It was also confirmed that the import of the precursors into mitochondria can be separated into two steps, the translocation of the precursor peptides into the inside of mitochondria across the membranes and the processing of the imported precursors by the processing proteases in the inside of the organelle.
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