2005 Fiscal Year Final Research Report Summary
Study on a novel function of N-glycans in the cytosol.
| Project/Area Number |
16570105
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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 |
Structural biochemistry
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| Research Institution | The Tokyo Metropolitan Organization of Medical Science |
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Principal Investigator |
KAWASHIMA Ikuo The Tokyo Metropolitan Organization of Medical Science, Tokyo Metropolitan Institute of Medical Science, Researcher, 東京都臨床医学総合研究所, 研究員 (40146824)
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| Co-Investigator(Kenkyū-buntansha) |
OGURA Kiyoshi The Tokyo Metropolitan Organization of Medical Science, Tokyo Metropolitan Institute of Medical Science, Researcher, 東京都臨床医学総合研究所, 研究員 (70233492)
TAI Tadashi The Tokyo Metropolitan Organization of Medical Science, Tokyo Metropolitan Institute of Medical Science, Researcher, 東京都臨床医学総合研究所, 研究員 (70112092)
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| Project Period (FY) |
2004 – 2005
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| Keywords | N-glycan / quality control of glycoprotein / ER-associated degradation |
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| Research Abstract |
The aim of this study is to clarify the novel function of N-glycans, in particular, high mannose oligosaccharides bound with unfolded proteins or insufficient polymer proteins in the cytosol. N-glycosylation of proteins in the endoplasmic reticulum (ER) plays a key role in the protein quality control. We previously reported that N-glycans serve as a degradation signal by an ubiquitin-ligase family in the cytosol. These studies clearly indicated that an approach from carbohydrate binding proteins is effective for the elucidation of carbohydrate functions, which has not been uncovered yet. The protein portions of unfolded glycoproteins, which are translocated from the ER to the cytosol by the quality control mechanism, are degradaded by an ubiquitin proteasome system. On the other hand, the carbohydrate portions are cleaved by enzymes such as PNGase and endo H enzyme. Subsequently, the oligosaccharides are degraded to Man5GlcNAc by α-mannosidase in the cytosol. It is postulated that the N-glycans are incorporated into lysosome by its specific transporter. During the past two years from 2004, we tried to isolate and characterize the carbohydrate binding proteins with the oligosaccharides that prepared from N-linked glycoproteins with PNGase and H enzyme. Although we used various high mannose oligosaccharides as probes, we could not detect any proteins in the cytosol. It is considered that assay methods used in the study may have not been reliable. Thus, it would be necessary for further experiments not only to advance the assay systems but also to isolate and characterize sugar binding proteins on organelles such as the lysosome as well. After isolation of the sugar binding proteins, it would be needed to analyze them in detail by means of molecular biology, biochemistry, and immunology.
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Research Products
(19 results)
