Journal Article

AtKUP1: a dual-affinity K+ transporter from Arabidopsis

Fu, H.H, Luan, S

1998

Overview

Plant roots contain both high- and low-affinity transport systems for uptake of K+ from the soil. In this study, we characterize a K+ transporter that functions in both high- and low-affinity uptake. Using yeast complementation analysis, we isolated a cDNA for a functional K+ transporter from Arabidopsis (referred to as AtKUP1 for Arabidopsis thaliana K+ uptake). When expressed in a yeast mutant, AtKUP1 dramatically increased K+ uptake capacity at both a low and high [K+] range. Kinetic analyses showed that AtKUP1-mediated K+ uptake displays a \"biphasic\" pattern similar to that observed in plant roots. The transition from the high-affinity phase (Km of 44 micromolars) to the low-affinity phase (Km of 11 mM) occurred at 100 to 200 micromolars external K+. Both low- and high-affinity K+ uptake via AtKUP1 were inhibited by 5 mM or higher concentrations of NaCl. In addition, AtKUP1-mediated K+ uptake was inhibited by K+ channel blockers, including tetraethylammonium, Cs+, and Ba2+. Consistent with a possible function in K+ uptake from the soil, the AtKUP1 gene is primarily expressed in roots. We conclude that the AtKUP1 gene product may function as a K+ transporter in Arabidopsis roots over a broad range of [K+] in the soil

• Publisher: American Society of Plant Physiologists
• Subject: ADN / Amino Acid Sequence / AMINO ACID SEQUENCES / Amino acids / ANTIMETABOLITE / ANTIMETABOLITES / ANTIMETABOLITOS / Arabidopsis / Arabidopsis - genetics / Arabidopsis - metabolism / Arabidopsis Proteins / ARABIDOPSIS THALIANA / ARN MENSAJERO / ARN MESSAGER / BARIO / BARIUM / BARYUM / Base Sequence / Biological Transport / Biological Transport - drug effects / CAESIUM / Carrier Proteins / Carrier Proteins - genetics / Carrier Proteins - metabolism / Cation Transport Proteins / Cations, Monovalent / Cations, Monovalent - metabolism / CELL MEMBRANES / CESIO / CESIUM / CHEMICAL COMPOSITION / CHLORURE DE SODIUM / CLORURO SODICO / COMPLEMENTARY DNA / Complementation / COMPOSICION QUIMICA / COMPOSITION CHIMIQUE / DNA / DNA, Complementary / DNA, Complementary - genetics / DNA, Plant / DNA, Plant - genetics / Dose-Response Relationship, Drug / drug effects / EXPRESION GENICA / EXPRESSION DES GENES / GENBANK/AF033118 / GENE / GENE EXPRESSION / GENES / Genes, Plant / Genetic Complementation Test / GENETIC TRANSFORMATION / genetics / ION / ION TRANSPORT / ION UPTAKE / IONES / IONS / Kinetics / MEMBRANAS CELULARES / MEMBRANE CELLULAIRE / MESSENGER RNA / metabolic inhibitors / metabolism / MOLECULAR SEQUENCE DATA / NUCLEOTIDE SEQUENCE / nucleotide sequences / pharmacology / Plant cells / PLANT PROTEINS / Plant Roots / Plant Roots - metabolism / Plants / plasma membrane / PLASMA MEMBRANES / POTASIO / POTASSIUM / Potassium - metabolism / Potassium Channel Blockers / PROTEINAS / PROTEINE / PROTEINS / RACINE / RAICES / REGULATION / ROOTS / SACCHAROMYCES CEREVISIAE / SALINIDAD / SALINITE / SALINITY / SECUENCIA NUCLEOTIDICA / Sequence Analysis, DNA / Sequence Homology, Amino Acid / SEQUENCE NUCLEOTIDIQUE / Sodium / Sodium - pharmacology / SODIUM CHLORIDE / STRUCTURAL GENES / Tissue Distribution / TRANSFORMACION GENETICA / TRANSFORMATION GENETIQUE / Yeasts / Yeasts - genetics