1987 Fiscal Year Final Research Report Summary
Regulation of protein biosynthesis at the level or polypeptide chain elongation
| Project/Area Number |
61470125
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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 |
応用生物化学・栄養化学
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| Research Institution | Iwata University |
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Principal Investigator |
EJIRI Shin-ichiro Faculty of Agriculture, Iwate University, Assoc, Professor, 農学部, 助教授 (90005629)
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| Project Period (FY) |
1986 – 1987
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| Keywords | protein biosynthesis / elongation factor / EF-1 / protein kinase / protein phosphatase / silk gland |
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| Research Abstract |
Eukaryotic elongation factor EF-1 which concerns the binding of aa-tRNA to ribosome, is constructed of four subunits (<alpha><beta><beta><gamma>) in many eukaryotes. <alpha> and <beta><beta>'<gamma> correspond functionally to prokaryotic EF-Tu and EF-Ts, respectively. Interestingly, both <beta> and <beta>' have EF-Ts-like activity to stimulate <alpha> dependent aa-tRNA binding and GDP-GTP exchange reactions. One of the major translational control mechanism in eukaryotes is phosphorylation of various components of the translational apparatus, such as initiation factor eIF-2. Howerer, little is known as for the translational control at elongation. In this studies, <beta>-kinase which phosphorylates <beta> subunit was purified from cytoplasm of wheat germ. Purified <beta>-kinase has molecular weight of 94k(53 and 35k subunits). It uses ATP and GTP as phosphate donors, and phosphorylates Ser and Thr residues of <beta> subunit. Then, <beta>-phosphatase was purified from silk gland using (^<32>)P)<beta> <beta>'<gamma> as a substrate. Purified <beta>-phosphatase is constructed of 34 and 24k subunits. By the phospharylation of native-<beta><beta>'<gamma> with <beta>-kinase,<beta> <beta>'<gamma> activities assayed by aa-tRNA binding and GDP-GTP exchange reactions were stimulated about 2-fold. Interstingly, native-<beta><beta>'<gamma> treated with <beta>-phosphatase lost its activities, and restored the activities by phosphorylation with <beta>-kinase. These results demonstrate clearly that the phosphorylation of <beta> is essential for the protein biosynthesis.
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