| Project/Area Number |
01480493
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Biological pharmacy
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| Research Institution | Kyushu University |
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Principal Investigator |
KATO Keitaro Kyushu University, Faculty of Pharmaceutical Sciences, Professor, 薬学部, 教授 (70037571)
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| Co-Investigator(Kenkyū-buntansha) |
HIMENO Masaru Kyushu University, Faculty of Pharmaceutical Sciences, Associate Professor, 薬学部, 助教授 (50037602)
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| Project Period (FY) |
1989 – 1990
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| Project Status |
Completed (Fiscal Year 1990)
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| Budget Amount *help |
¥6,900,000 (Direct Cost: ¥6,900,000)
Fiscal Year 1990: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1989: ¥5,800,000 (Direct Cost: ¥5,800,000)
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| Keywords | Membrane traffic / cDNA cloning / Target signal / Endosome / Autolysosome / Fusion / エンドゾ-ム / Mー6ーP受容体 / M-6-P受容1本 |
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| Research Abstract |
Rat liver lysosomal membrane glycoprotein having a molecular weight of 107K (LGP107) was purified and antibodies against the protein were raised on rabbits. A conjugate of its Fab' fragment with horseradish peroxidase (HPR-antiLGP107Fab') was prepared as a probe for the subcellular antigen. Electronimmunocytochemistry in primary cultured rat hepatocytes showed that LGP107 resided primarily within lysosomes and was associated with luminal amorphous materials as well as limiting membranes. In addition, LGP107 was shown to be substantially distributed throughout the endocyctic vacuolar system. The glycoprotein was found clustered in coated pits at the cell surface and localized along the surrounding membranes in endocyctic vesicles. When cultured cells were exposed to HRP-antiLGP107 Fab', the antibody which was bound to its antigen within the coated pits was internalized via a system of endocyctic vesicles, and transported to lysosomes. These data suggest that LGP107 circulates between th
… More
e cell surface and lysosomes through the endocytic membrane traffic in hepatocytes.
Four cDNA clones for lysosomal membrane glycoproteins such as acid phosphatase, LGP107, LGP96, and LGP85, were isolated to examine target signal of lysosomal membranes to lysosomes. Three of which except LGP85 have highly hydrophobic domain near their C terminals as a membrane anchoring domain and short cytosolic domain which may play a role to get information from outside of lysosomes. Also the anchoring domains including the short cytosolic tails of these three lysosomal membrane glycoproteins have a high sequence similarity (more than 60%) among them. However, LGP87 has two hydrophobic domains, suggesting two membrane anchoring domains at N and C terminus and a short cytosolic tail at C terminal. The membrane anchoring domain at N terminal is a signal peptide which is not cleaved off. Lysosomal membrane glycoproteins so far cloned showed no example such as LGP85 having two membrane anchoring domains. Fusions between purified endosomes and autolysosomes isolated from rat livers received either [^<125>I] asialofetuin or asialofetuin conjugated with HRP were examined and fusion products were determined as radioactive DAB polymers on milipore filters. The fusion between endosomes and autolysosomes showed that although endosome-endosome fusion requires ATP, endosome-autolysosome fusion proceeded without ATP. Less
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