| Budget Amount *help |
¥5,500,000 (Direct Cost: ¥5,500,000)
Fiscal Year 1987: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1986: ¥4,300,000 (Direct Cost: ¥4,300,000)
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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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