| Project/Area Number |
02454535
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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 |
物質生物化学
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| Research Institution | The University of Tokyo |
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Principal Investigator |
MUROFUSHI Hiromu The University of Tokyo Faculty of Science Associated Professor, 理学部, 助教授 (70101128)
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| Co-Investigator(Kenkyū-buntansha) |
SUZUKI Koichi University of Tokyo Institute for Applied Microbiology Professor, 応用微生物研究所, 教授 (80011948)
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| Project Period (FY) |
1990 – 1992
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| Project Status |
Completed (Fiscal Year 1992)
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| Budget Amount *help |
¥6,800,000 (Direct Cost: ¥6,800,000)
Fiscal Year 1992: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1991: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1990: ¥4,300,000 (Direct Cost: ¥4,300,000)
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| Keywords | Microtubule / Microtubule-associated proteins / MAP4 / Tau / NMR / Protein kinase C / Cdc2 kinase / DNA polymerase alpha / サイクリンB / 中間径繊維 / ビメンチン / リン酸化 / プロテインキナ-ゼC / cdc2キナ-ゼ / チュ-ブリン / 核磁気共鳴 / DNAポリメラ-ゼα |
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| Research Abstract |
Microtubule-associated proteins (MAPs) have functions to promote tubulin polymerization and to stabilize microtubules. It is considered that they have a key role to govern the stability of microtubules in the cell. Following results were obtained by our study on the structure and functions of MAPs.
1. A peptide consisting of an AP sequence, a tubulin-binding motif shared by MAP4, MAP2 and tau, was synthesized and the interaction of this peptide with tubulin was investigated by NMR. It was found that Lys and Arg in the peptide took part in the binding with tubulin and that Val in the peptide and Tyr in a tubulin molecule interacted with each other.
2. cDNA cloning and sequencing of bovine MAP4 revealed that it consists of N-terminal domain with high percentage of acidic amino acid residues and C-terminal domain witch is subdivided into a region rich in Pro residues and a region containing four repeats of AP sequences. A high homology in the primary sequences of C-terminal domains of MAP4,
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MAP2 and tau was observed with little homology in the N-terminal domains of the MAPs.
3. Studies on the nature of bacterially expressed fragments of MAP4 showed that the region with AP sequences specifically interacts with tubulin molecules and that the Pro-rich region enhances the interaction.
4. Phosphorylation of specific amino acid residues in the Pro-rich region by protein kinase C and cdc2 kinase reduced the activity of MAP4 to promote tubulin polymerization. This result suggests the presenceof a control mechanism by protein kinases to regulate the activity of MAPs to promote tubulin polymerization and to stabilize microtubules in the cell.
5. It has been reported that a part of MAPs in an actively proliferating cell are transported to the nuclus, suggesting that phosphorylated MAPs have unknown functions related to cell proliferation in the nucleus. Our study revealed that MAPs stimulated the activity of DNA polymerase a purifid from many types of eukaryotic cells. It was also shown that phosphorylated MAPs had higher activity to stimulate DNA polymerase a than unphosphorylated MAPs. Less
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