XB-ART-18892
Science
1995 Dec 08;2705242:1660-3. doi: 10.1126/science.270.5242.1660.
Show Gene links
Show Anatomy links
Sodium-driven potassium uptake by the plant potassium transporter HKT1 and mutations conferring salt tolerance.
???displayArticle.abstract???
Sodium (Na+) at high millimolar concentrations in soils is toxic to most higher plants and severely reduces agricultural production worldwide. However, the molecular mechanisms for plant Na+ uptake remain unknown. Here, the wheat root high-affinity potassium (K+) uptake transporter HKT1 was shown to function as a high-affinity K(+)-Na+ cotransporter. High-affinity K+ uptake was activated by micromolar Na+ concentrations; moreover, high-affinity Na+ uptake was activated by K+ (half-activation constant, 2.8 microM K+). However, at physiologically detrimental concentrations of Na+, K+ accumulation mediated by HKT1 was blocked and low-affinity Na+ uptake occurred (Michaelis constant, approximately 16 mM Na+), which correlated to Na+ toxicity in plants. Point mutations in the sixth putative transmembrane domain of HKT1 that increase Na+ tolerance were isolated with the use of yeast as a screening system. Na+ uptake and Na+ inhibition of K+ accumulation indicate a possible role for HKT1 in physiological Na+ toxicity in plants.
???displayArticle.pubmedLink??? 7502075
???displayArticle.link??? Science
References :
Walker,
High-affinity potassium uptake in plants.
1996, Pubmed