PMID:12376644

Citation	Bañuelos, MA, Garciadeblas, B, Cubero, B and Rodríguez-Navarro, A (2002) Inventory and functional characterization of the HAK potassium transporters of rice. Plant Physiol. 130:784-95
Abstract	Plants take up large amounts of K(+) from the soil solution and distribute it to the cells of all organs, where it fulfills important physiological functions. Transport of K(+) from the soil solution to its final destination is mediated by channels and transporters. To better understand K(+) movements in plants, we intended to characterize the function of the large KT-HAK-KUP family of transporters in rice (Oryza sativa cv Nipponbare). By searching in databases and cDNA cloning, we have identified 17 genes (OsHAK1-17) encoding transporters of this family and obtained evidence of the existence of other two genes. Phylogenetic analysis of the encoded transporters reveals a great diversity among them, and three distant transporters, OsHAK1, OsHAK7, and OsHAK10, were expressed in yeast (Saccharomyces cerevisiae) and bacterial mutants to determine their functions. The three transporters mediate K(+) influxes or effluxes, depending on the conditions of the experiment. A comparative kinetic analysis of HAK-mediated K(+) influx in yeast and in roots of K(+)-starved rice seedlings demonstrated the involvement of HAK transporters in root K(+) uptake. We discuss that all HAK transporters may mediate K(+) transport, but probably not only in the plasma membrane. Transient expression of the OsHAK10-green fluorescent protein fusion protein in living onion epidermal cells targeted this protein to the tonoplast.
Links	PubMed PMC166606 Online version:10.1104/pp.007781
Keywords	Amino Acid Sequence; Carrier Proteins/genetics; Carrier Proteins/metabolism; Cation Transport Proteins/genetics; Cation Transport Proteins/metabolism; Escherichia coli/genetics; Gene Expression Regulation, Plant; Methionine/analogs & derivatives; Methionine/isolation & purification; Methionine/metabolism; Molecular Sequence Data; Mutation; Onions/cytology; Oryza sativa/genetics; Oryza sativa/metabolism; Phylogeny; Plant Epidermis/cytology; Plant Proteins/genetics; Plant Proteins/metabolism; Plant Roots/genetics; Plant Roots/metabolism; Plant Shoots/genetics; Plant Shoots/metabolism; Potassium/metabolism; Selenium Compounds/isolation & purification; Selenium Compounds/metabolism; Yeasts/genetics
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ORYSJ:HAK1	involved_in	GO:0006813: potassium ion transport	ECO:0000314: direct assay evidence used in manual assertion		P		Seeded From UniProt	complete
ORYSJ:HAK1		GO:0006813: potassium ion transport	ECO:0000314:		P		(Fig.7) K+ starved rice and yeast expressing OsHAK1 were grown on K+ containing media. The rate of depletion followed a Michaelis-Menten relationship in both rice and yeast mutants.	complete CACAO 4948

References

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