Research Project
Grant-in-Aid for Scientific Research (B)
During the project period for two years, we obtained the following results concerning metal transporters and proton pumps in the vacuolar membranes.(1) Cation/H^+ exchangers : Rice has five isoforms of cation/H^+ exchanger (CAX). Our study revealed that these five isoforms varied with metal ion selectivity and tissue specificity of gene expression. CAX1a among them is expressed in all tissues examined and is highly expressed in companion and endodermis cells, which has high concentration of Ca^<2+>. We estimate that CAX1a functions to reserve Ca^<2+> into vacuoles and is involved in the Ca^<2+> detoxification.(2) Vacuolar zinc transporter (MTP1) : Arabidopsis MTP1 has been demonstrated to be located to the vacuolar membrane. The knockout mutant of MTP1 was highly sensitive to high concentrations (more than 0.2 mM) of zinc. Thus, MTP1 might be involved in the detoxification of zinc by transporting ion in the cytoplasm into vacuoles. By heterologous expression of MTP1 in yeast and direct measurement of zinc transport using Zn-65, we demonstrated that MTP1 functions as Zn^<2+>/H^+ exchanger.(3) Vacuolar proton pump : Vacuolar membrane H+-pyrophosphatase (H^+-PPase) acidifies vacuoles and maintains the pH gradient across the membrane. Our experiments revealed that a knockout mutant of H^+-PPase could not grow normally, suggesting that H+-PPase is one of the essential membrane transport systems in plants. We also determined the membrane topology of H^+-PPase and essential motifs in the enzyme. Our structural model has been accepted as a standard of H^+-PPases in various organisms.
All 2006 2005 2004
All Journal Article (71 results) Book (4 results)
Plant Cell Physiol. 47
Pages: 96-106
Biosci. Biotechnol. Biochem. 70
Pages: 980-987
Pages: 309-318
J. Exp. Botany 57
Pages: 1373-1379
10017158016
Biosci.Biotechnol.Biochem. 70
10018532678
J.Exp.Bot. 57
Biosci.Biotechnol.Biochem. Apr.issue (In press)
J.Exp.Botany 57
Plant Cell Physiol. 46
Pages: 407-415
Soil Sci. Plant Nutr. 51
Pages: 135-139
Biochim. Biophys. Acta 1708
Pages: 393-403
FEBS Letters 579
Pages: 3625-3631
J. Biochem. 138
Pages: 183-191
Annals Bot. 96
Pages: 457-460
J. Proteome Res. 4
Pages: 1755-1780
Pages: 1568-1577
Pages: 1735-1740
Pages: 5814-5820
10015598502
Soil Sci.Plant Nutr. 51
110004704730
Biochim.Biophys.Acta-Bioenergetics 1708
120000979445
J.Biochem. 138
Annals of Botany 96
J.Proteome Res. 4
FEBS Lett. 579
Biochemistry and Molecular Biology of Plants. (Japanese edition).
Mechanisms in Fresh Bodies : Function of Aquaporins and Its Relation with Diseases.
Pages: 20-32
Biochim.Biophys.Acta 1708
Annlas Bot. 96
Plant and Cell Physiology 46
J. Biol. Chem. 279
Pages: 812-819
J. Exp. Botany 55
Pages: 585-594
Mol. Biol. Cell 15
Pages: 3393-3405
Plant Cell Physiol. 45
Pages: 672-683
Pages: 951-957
Pages: 823-830
Pages: 35106-35112
Pages: 1313-1319
Plant Mol.Biol. 56
Pages: 839-848
Pages: 1749-1758
J.Biol.Chem. 279
120000979762
J.Exp.Botany 55
Mol.Biol.Cell. 15
10013128417
10013345141
10014214266
Journal of Biological Chemistry 279
Journal of Experimental Botany 55
Molecular Biology of the Cell 15
Plant and Cell Physiology 45
Plant Molecular Biology 56
化学と生物 42
Pages: 41-42
10012135532