1988 Fiscal Year Final Research Report Summary
Molcular control of platelets function by protein kinases
| Project/Area Number |
62580116
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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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 | Mie University |
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Principal Investigator |
NAKA Michiko Mie University School of Medicine, Assistant, 医学部, 助手 (10093139)
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| Project Period (FY) |
1987 – 1988
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| Keywords | Platet / protein phosphorylation / Myosin light chain kinase / Cキナーゼ |
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| Research Abstract |
Biological function of blood plateletsincluding aggregating, secretion and clot retraction are expressed through cellular contractile activity. The Ca^<2+>-calmodulin-dependent phosphorylation of 20K-Da myosin light chain(MLC)catalyzed by mlc kinase may be the major regulation system of contractile proteins in platelets,as well as in smooth muscle cells. Recentry, we found that protein kinase C is responsible for phosphorylation of 20K-Da MLC during platelet activation (particularly in resppnse to stimulation by TPA). Three forms of 20K-Da MLC,unphosphorylated, monophosphorylated and diphosphorylated MLC were observed in thrombin-stimulated human platelets by two different gel electrophoretic method; in the presence of glycerol urea or in two dimensions. after mon/-or diphosphorylated 20K-Da MLC from thrombin stimulated platelet was digsted with trypsin the analysis using two-dimensional peptide mapping demonstrated that two different sites were phosphorylated by MLC kinase and protein kinase C. Activation of protein kinase C and mobilzation of Ca^<2+>are induced separately in intact cells by treatment with TPA and Ca^<2+>ionophore respectively. We invastigated whether double phosphorylations of 20K-Da MLC were induced by TPA or Ca^<2+>ionophore. TPA activated both MLC kinase and protein kinase C but Ca^<2+>ionophre activated only MLC kinase.
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