2004 Fiscal Year Final Research Report Summary
Structural studies on antigen presents system based on the 20S bovine proteasome.
| Project/Area Number |
13680749
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Biophysics
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| Research Institution | Research Reactor Institute, Kyoto University (2003-2004)
Himeji Institute of Technology (2001-2002) |
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Principal Investigator |
MORIMOTO Yukio Kyoto University, Research Reactor Institute, Prof., 原子炉実験所, 教授 (80200450)
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| Project Period (FY) |
2001 – 2004
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| Keywords | poroteasome / supramolecules / crystal structure / immuno-respose |
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| Research Abstract |
Proteasome is a most important protease particle composed of 28 hetero-subunits. It functions a proteolysis in the cell to maintain stable it, and has the molecular weight of 750kDa, a large multifunctional enzyme. Proteasomes are also having an immuno-response by generating antigenic peptides presented by class I molecules of major histocompatibility complex when the proteasome activator (PA28) binds proteasomes. In this work, a structural investigation of the 20S proteasome from bovine liver and the proteolytic mechanism inside β-subunits are discussed.
20S proteasomes are isolated and purified from bovine liver, and crystallized (Y.Morimoto, et al., J.B., 1995). It has good quality for a structure analysis (Y.Tomisugi, et al., J.B., 2000). A structural refinement (M.Unno, et.al., Structure, 2002) with non-crystallographic symmetry operations goes down the crystallographic R-factor to 25.0% (FreeR=29.4%). One of features for a crystal structure of proteasomes is a location of acidic amino acids of the central cavity in proteasomes. It seems likely to present the mechanism of strict proteolysis against unneeded protein or antigen-presenting. Constitutive 20S proteasomes have three active subunits, β1, β2 and β5, which are replaced in the immunoproteasome by interferon-γ-inducible subunits β1i, β2i and β5i, respectively. A catalytic activity is discussed that in the β7 subunit N104, T1, D59 and R99 hold peptide chain by helping of Y88 in β1 subunit. The reaction is completed when the α-amino group donates a proton to the nucleophile.
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Research Products
(12 results)
