1988 Fiscal Year Final Research Report Summary
Molecular mechanisms of biosynthesis and degradation of yolk proteins of the silkworm,Bombyx mori
| Project/Area Number |
62480047
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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 |
蚕糸学
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| Research Institution | Nagoya University |
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Principal Investigator |
YAMASHITA Okitsugu Nagoya University, Faculty of Agriculture, Associate Prof., 農学部, 助教授 (50023411)
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| Co-Investigator(Kenkyū-buntansha) |
YAGINUMA Toshinibu Nagaya University, Faculty of Ageiculture,Assistant, 農学部, 助手 (60135332)
KOBAYASHI Michihiro Nagaya University, Faculty of Ageiculture,Assistant, 農学部, 助手 (60111837)
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| Project Period (FY) |
1987 – 1988
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| Keywords | Bombyx mori / oogenesis / embryogenesis / egg-specific protein / プロテアーゼ |
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| Research Abstract |
Yolk proteins the silkworm, Bombyx mori consist of three major proteins and among them, egg-specific (ESP) behaves differently from others. The present study was carried out to elucidate the molecular mechanisms of biosynthesis and degradation of this protein. From the genomic library, ESP gene was isolated and the partial structure was carified. cDNA of ESP was constracted and sequenced. The complete amino acid sequence was deduced from the nucleotids sequence. The in vitro translation experiment concluded that esp was translated as a nascent peptide-aving segnal sequence. The post-translational modification occurred sequentially through signal cleavage, glycosylation, phosphorylation. ESP contains appreciable amounts of zinc, which suggest that ESP interacts with nucleic acids.
During embryogenesis, ESP is degraded sequentially into three peptides by a unique protease. This protease had the high specificity to ESP without atacking to the other yolk proteins. Cleavage sites were identified by analysing N-termina amino acid sequence as at the carboxyl site of lysine^<114> and argine^<210>. The activity of this protease chenged temporaly according to the embryogenesis. This developmental profile in activity well corresponded to the changes in mRNA activity. The in vitro translation experiment showed that the enzyme protein is synthesized as a nascent peptide and then processed into a mature form of protein through signal cleavage. The nascent peptide showed the biological activity which was comparable to the processed proteins. This is the first report of the biologically active products of translation.
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