1997 Fiscal Year Final Research Report Summary
Structural Basis of Active Transport by Ion Pumps
| Project/Area Number |
08044195
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Field |
Biophysics
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| Research Institution | The University of Tokyo |
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Principal Investigator |
TOYOSHIMA Chikashi The University of Tokyo, Institute of Molecular and Cellular Biosciences, Professor, 分子細胞生物学研究所, 教授 (70172210)
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| Co-Investigator(Kenkyū-buntansha) |
OGAWA Haruo The University of Tokyo, Faculty of Medicine, Research Associate, 大学院・医学系研究科, 助手 (40292726)
STOKES David L New York University Medical Center, Scirball Institute of Molecular Medicine, As, 準教授
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| Project Period (FY) |
1996 – 1997
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| Keywords | ion pump / calcium pump / active transport / three-dimensional structure / electron microscopy / structural analysis / membrane proteins |
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| Research Abstract |
The goal of this project is to elucidate the structural basis of active ion transport by analysing the three-dimensional structures of ion pumps at various stages in the transport cycle. We have been working on calcium ATPase of sarcoplasmic reticulum, which is a representative member of P-type ion pumps and responsible for relaxing muscle cells by pumping calcium ions from cytoplasm. Since only tubular and very thin three-dimensional crystals can be formed, we have put much efforts to improve the technology for image analysis. Japan side has developed programs for helical analysis and combined them with a new microscope installed in New York University to study the structures of the tubular crystals with CrATP or thapsigargin bound. As a result, we have succeeded in determining the ATP-binding site (Biopys.J., publised) and obtaining 8 * resolution maps. In these maps, 10 transmembrane helices and ion pathway can be seen (Nature, in press). These good results have been possible only with international collaboration, and 4 international travels have been made. As to the three-dimensional crystals formed in the presence of calcium, much efforts are still needed for establishing the methodology. At present, a 9 *-resolution map has been obtained showing the view of the crystal along the lipid bilayr. The structure is much different from that obtained from the tubular crystals formed in the absence of calcium. The manuscript on this work has been submitted to Biohys.J.
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