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Reference Detail
| Reference | ||
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| Author | Horie T. , Brodsky D.E. , Costa A. , Kaneko T. , Lo Schiavo F. , Katsuhara M. , Schroeder J.I. | |
| Title | K+ Transport by the OsHKT2;4 Transporter from Rice with Atypical Na+ Transport Properties and Competition in Permeation of K+ over Mg2+ and Ca2+ Ions. | |
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Abstract: Members of class II of the HKT transporters, which have thus far only been isolated from grasses, were found to mediate Na(+)-K(+) cotransport and at high Na(+) concentrations preferred Na(+)-selective transport, depending on the ionic conditions. But the physiological functions of this K(+)-transporting class II of HKT transporters remain unknown in plants, with the exception of the unique class II Na(+) transporter OsHKT2;1. The genetically tractable rice (Oryza sativa; background Nipponbare) possesses two predicted K(+)-transporting class II HKT transporter genes, OsHKT2;3 and OsHKT2;4. In this study, we have characterized the ion selectivity of the class II rice HKT transporter OsHKT2;4 in yeast and Xenopus laevis oocytes. OsHKT2;4 rescued the growth defect of a K(+) uptake-deficient yeast mutant. Green fluorescent protein-OsHKT2;4 is targeted to the plasma membrane in transgenic plant cells. OsHKT2;4-expressing oocytes exhibited strong K(+) permeability. Interestingly, however, K(+) influx in OsHKT2;4-expressing oocytes did not require stimulation by extracellular Na(+), in contrast to other class II HKT transporters. Furthermore, OsHKT2;4-mediated currents exhibited permeabilities to both Mg(2+) and Ca(2+) in the absence of competing K(+) ions. Comparative analyses of Ca(2+) and Mg(2+) permeabilities in several HKT transporters, including Arabidopsis thaliana HKT1;1 (AtHKT1;1), Triticum aestivum HKT2;1 (TaHKT2;1), OsHKT2;1, OsHKT2;2, and OsHKT2;4, revealed that only OsHKT2;4 and to a lesser degree TaHKT2;1 mediate Mg(2+) transport. Interestingly, cation competition analyses demonstrate that the selectivity of both of these class II HKT transporters for K(+) is dominant over divalent cations, suggesting that Mg(2+) and Ca(2+) transport via OsHKT2;4 may be small and would depend on competing K(+) concentrations in plants. |
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| Journal | Plant Physiol. | |
| Country | Japan | |
| Volume | 156(3) | |
| Pages | 1493-507 | |
| Year | 2011 | |
| PubMed ID | 21610181 | |
| PubMed Central ID | - | |
| DOI | - | |
| URL | - | |
| Relation | ||
| Gene | HKT1 HKT3 HKT9 | |
| INSD | - | |
| Strain | Wild Core Collection | - |
| Induced Mutation Lines(NIG Collection) | - | |
| Sterile Seed Strain | - | |
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Lethal Embryo Mutantion Strain |
- | |
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Stages in Each Organ - Muant Lines (Gene) |
- | |
| Cultivated Varieties(NIG Collection) | - | |
| Stages in Each Organ | - | |
