| Project/Area Number |
11440235
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
植物生理
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| Research Institution | Nagoya University |
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Principal Investigator |
TORIIYAMA Shoshi Nagoya Universiry, Bioscience Center, Professor, 生物分子応答研究センター, 教授 (40013338)
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| Project Period (FY) |
1999 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥10,200,000 (Direct Cost: ¥10,200,000)
Fiscal Year 2001: ¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 2000: ¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 1999: ¥4,400,000 (Direct Cost: ¥4,400,000)
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| Keywords | Guard cell / Abscisic acid / Protein kinase / ABR kinase / Calcium channel / AtTPCl / サリチル酸 / 活性酸素 / AAPK / AAPKキナーゼ / KAT1 / カリウムチャネル |
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| Research Abstract |
We have found a protein kinase (ABR kinase) which is activated upon treatment of stomatal guard cells with abscisic acid (ABA). A potasium channel KATl has been shown to be phosphorylated and inactivated by ABR kinase. AAPK (ABA-activated protein kinase) which may be identical to ABR kinase was cloned from Vicia guard cells by Assmann's group. We isolated cDNA encoding AAPK from Arabidopsis, and expressed it in E. coli as a His-tagged protein. The recombinant protein showed an expected molecular mass of 42 kD on SDS-PAGE but had no enzyme activity. Western blot using anti-His-AAPK indicated that AAPK was localized exclusively in guard cells of Vicia plant, however, its molecular mass was 48 kD, suggesting AAPK was posttranslationally modified. His-AAPK was phosphorylated when incubated with the protoplast extract prepared from ABA-treated guard cells. This indicates that a protein kinase which phosphorylate AAPK (AAPK kinase) is present in guard cells and activated by ABA-treatment. The activation was peaked 1-2 min after ABA-treatment, preceding the activation of AAPK ( 5-10 min after treatment). The results suggest that AAPK is phosphorylated and activated by AAPK kinase, and KAT1 is regulated by a protein kinase cascade consists of these protein kinases.
ABA induces an increase in |Ca^<2+>|_<cyt> in guard cells prior to the activation of protein kinases. The |Ca^<2+>|_<cyt> increase is caused by gating of Ca^<2+> channel(s) on the plasma membrane. A cDNA coding a putative Ca^<2+> channel (AtTPCl) was cloned from Arabidopsis. The overall structure of AtTPCl is similar to the half of the general structure of α-subunit of voltage-gated Ca^<2+> channels from animals. AtTPCl rescued the Ca^<2+> uptake activity of a yeast Ca^<2+> channel mutant cchl. Analysis using sucrose-induced luminescence in aequorin-expressing Arabidopsis provided indirect evidences showing that AtTPCl is a voltage-gated Ca^<2+> permeable channel.
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