| Project/Area Number |
12138205
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research on Priority Areas
|
| Allocation Type | Single-year Grants |
|---|
| Review Section |
Biological Sciences
|
|---|
| Research Institution | Koyoto Univeristy |
|---|
Principal Investigator |
HARA Ikuko Kyoto Univ., Grad. School of Sci., Prof., 大学院・理学研究科, 教授 (00241232)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
HAYASHI Makoto Okazaki National Research Institutes, National Institute for Basic Biology, Assoc. Prof., 岡崎国立共同研究機構・基礎生物学研究所, 助教授 (50212155)
|
|---|
| Project Period (FY) |
2000 – 2003
|
| Project Status |
Completed (Fiscal Year 2003)
|
| Budget Amount *help |
¥63,900,000 (Direct Cost: ¥63,900,000)
Fiscal Year 2003: ¥21,300,000 (Direct Cost: ¥21,300,000)
Fiscal Year 2002: ¥21,300,000 (Direct Cost: ¥21,300,000)
Fiscal Year 2001: ¥21,300,000 (Direct Cost: ¥21,300,000)
|
|---|
| Keywords | Protein sorting / Protein storage vacuole / Seed / PAC vesicle / Storage protein / Vesicle transport / Vacuolar sorting signal receptor / Vacuolar sorting / タンパク質輸送 / 液胞プロセシング酵素 / 種子貯蔵タンパク質 / タンパク質貯蓄型液胞 / 12グロブリン / 2Sアルブミン / 輸送レセプター / EGFモチーフ / タンパク質蓄積型液胞 / GFP |
|---|
| Research Abstract |
The seeds of higher plants accumulate large quantities of storage protein. During seed maturation, storage protein precursors synthesized on rough endoplasmic reticulum are sorted to protein storage vacuoles, where they are converted into the mature forms and accumulated. We found that novel vesicles, PAC (precursor-accumulating) vesicles, mediate the mass transport of storage proteins to PSVs in maturing pumpkin seeds, Isolated PAC vesicles contain a large amount of the precursors of major storage proteins. On the membrane of the PAC vesicles, we found PV72, a type I integral membrane protein composed of a large lumenal domain and a transmembrane domain followed by a short cytosolic tail that contains a potential tyrosine-based motif. PV72 is specifically and transiently accumulated in maturing pumpkin seeds in association with the synthesis of storage proteins, but is not expressed in vegetative tissues. PV72 bound to peptides derived from pumpkin 2S albumin and also to the precursor of pumpkin 2S albumin in the presence of Ca^<2+> These observations imply that PV72 functions as a vacuolar sorting receptor for storage proteins in pumpkin seeds. We demonstrated that a PV72 homologue, AtVSR1/AtELP, of Arabidopsis functions as a sorting receptor for storage proteins. The alvsr1 mutant mis-sorts storage proteins by secreting them from cells, resulting in an enlarged and electron-dense extracellular space in the seeds. Our findings demonstrate a receptor-mediated transport of seed storage proteins to protein storage vacuoles in higher plants.
|
