1992 Fiscal Year Final Research Report Summary
Involvement of phosphatidylinositol 3-kinase in cell growth
| Project/Area Number |
03454163
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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 |
Pathological medical chemistry
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| Research Institution | The University of Tokyo (1992)
Tokyo Metropolitan Institute of Gerontology (1991) |
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Principal Investigator |
TAKENAWA Tadaomi Institute of Medical Science, Univ. of Tokyo, Professor, 医科学研究所, 教授 (40101315)
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| Co-Investigator(Kenkyū-buntansha) |
SHIBASAKI Futoshi Tokyo Metropolitan Institute of Gerontology, Research associate, 生体情報研究部門, 研究員 (40241260)
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| Project Period (FY) |
1991 – 1992
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| Keywords | PI3 Kinase / Tyrosine kinase / Purification / SH_2 / Tyrosine phosphorylation |
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| Research Abstract |
Two types of phosphatidylinositol(PI) 3-kinase (PI3K) have been purified 6250-fold (PI3KI) and 1250-fold (PI3KII) from the cytosol fraction of bovine thymus, respectively. Purified PI3KI and PI3KII were found to be apparent molecular weight of 110 KDa and 190 KDa respectively by a gel filtration. On the other hand, on SDS gel electrophoresis molecular weight of PI3KI was also estimated as 110 KDa but PI3KII showed two bands of which molecular weight are 110 KDa and 85 KDa, suggesting a heterodimer form. Peptide mapping analysis also demonstrated that a 110 KDa protein contained in PI3KII is the same protein as PI3KI. Specific activity of PI3KI was calculated as 250 nmol/min/mg protein, while that of PI3KII was as 25 nmol/min/mg protein, indicating that monomer has higher activity than heterodimer. PI3KII but not PI3KI was co-immunoprecipitated with pp60^<v-src> and middle T/pp60^<c-src> even in the conditions where PI3Ks were not phosphorylated suggesting that non phosphorylated PI3K recognized pp60^<v-src> PI3KII was phosphorylated by pp60^<v-src> and bound to pp60^<v-src>. Anti-p85 (85 Kda subunit of PI3KII) antibody which precipitated PI3KII co-immunoprecipitated pp60^<v-src> in src-transformed cells suggesting that PI3KII bound to pp60^<v-src>. All these data shows that these PI3Ks are regulated independently.
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