1999 Fiscal Year Final Research Report Summary
Plant cysteine protease: multiple posttranslational processing and intracellular transport
| Project/Area Number |
09640776
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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 |
植物生理
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| Research Institution | TOKYO METOROPOLITAN UNIVERSITY |
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Principal Investigator |
MINAMIKAWA Takao Dept. of Biol. Science Professor, 理学研究科, 教授 (30087001)
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| Project Period (FY) |
1997 – 1999
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| Keywords | cysteine protease / endopeptidase / intracellular transport / Vigna mungo / seed germination / posttranslational processing / endoplasmic reticulum / vacuole |
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| Research Abstract |
A vacuolar cysteine proteinase, designated SH-EP, is expressed in the cotyledon of germinated Vigna mungo seeds, and is responsible for the degradation of storage proteins. SH-EP is a characteristic vacuolar proteinase possessing a carboxy-terminal endoplasmic reticulum (ER) retention secuence, KDEL. In the present work, immunocytochemical analysis of the cotyledon cells of V. mungo seeds was performed using seven kinds of antibodies to identify the intracellular transport of SH-EP from ER to protein storage vacuoles. A proform of SH-EP synthesized in ER accumulated at the edge of middle regions of ER where the transport vesicle was formed. The vesicle containing a large amount of proSH-EP, termed KV, budded off from ER, bypassed the Golgi complex and was sorted to protein storage vacuoles. This massive transport of SH-EP via KV was thought to mediate dynamic protein mobilization in the cotyledon cells of germinated seeds. We discuss the possibilities that the KDEL sequence of KDEL-tailed vacuolar cysteine proteinases functions as an accumulation signal at ER and that the mass transport of the proteinases by ER-derived KV-like vesicle is involved in the protein mobilization of plants.
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