title: Cloning and functional characterization of the high-affinity K+ transporter HAK1 of pepper.
abstract: High-affinity K+ uptake in plants plays a crucial role in K+ nutrition and different systems have been postulated to contribute to the high-affinity K+ uptake. The results presented here with pepper (Capsicum annum) demonstrate that a HAK1-type transporter greatly contributes to the high-affinity K+ uptake observed in roots. Pepper plants starved of K+ for 3 d showed high-affinity K+ uptake (Km of 6 microM K+) that was very sensitive to NH and their roots expressed a high-affinity K+ transporter, CaHAK1, which clusters in group I of the KT/HAK/KUP family of transporters. When expressed in yeast ( Saccharomyces cerevisiae ), CaHAK1 mediated high-affinity K+ and Rb+ uptake with Km values of 3.3 and 1.9 microM, respectively. Rb+ uptake was competitively inhibited by micromolar concentrations of NH and Cs+, and by millimolar concentrations of Na+.
authors.affiliation: Departamento de Nutrición Vegetal, Centro de Edafología y Biología Aplicada del, Segura-CSIC, Apartado de Correos 164, Murcia, 30100, Spain.
authors.forename: M Angeles
authors.initials: MA
authors.lastname: Martínez-Cordero
authors.forename: Vicente
authors.initials: V
authors.lastname: Martínez
authors.forename: Francisco
authors.initials: F
authors.lastname: Rubio
mesh_terms: D015152:Blotting, Northern; D002212:Capsicum / Q000235:genetics*; D027682:Cation Transport Proteins / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D009154:Mutation; D010802:Phylogeny; D018517:Plant Roots / Q000235:genetics; D011188:Potassium / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012413:Rubidium / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA
chemical_list: D027682:Cation Transport Proteins; D018076:DNA, Complementary; D012333:RNA, Messenger; D012413:Rubidium; D011188:Potassium