Rubidium (potassium) uptake by Arabidopsis: a comparison of uptake by cells in suspension culture and by roots of intact seedlings |
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Authors: | Polley L D Hopkins J W |
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Affiliation: | Department of Biology, Washington University, St. Louis, Missouri 63130. |
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Abstract: | Experiments are reported in which the uptake of 86Rb+, used as an analog of K+, into cultured cells of Arabidopsis thaliana is investigated. A single transport system is found with Km = 0.34 millimolar and Vmax = 14 nmoles per milligram of protein per hour. This system is blocked by the metabolic inhibitor carbonyl cyanide m-chlorophenyl hydrazone (CCCP) and by cold. At high concentrations of external K+ (above 1 millimolar), a significant fraction of total uptake is energy-independent. No evidence is found for more than one energy-dependent uptake system or for concentration-dependent modifications of a carrier as postulated in multiphasic transport models. |
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