Allosteric Regulation of Potassium Uptake in Plant Roots

作者：Paul Jensén, Sune Pettersson · 发表于：Physiologia Plantarum · 年份：1978 · DOI：10.1111/j.1399-3054.1978.tb02549.x · 被引用次数：107 · 研究领域：Plant nutrient uptake and metabolism、Plant Stress Responses and Tolerance、Ion Transport and Channel Regulation

Abstract In uptake experiments from nutrient solutions containing 2.0 mMK+labelled with86Rb+, the relationship between potassium uptake efficiency and internal potassium concentration of the roots, [K+]iwas found to be partly sigmoidal for intact plants of spring wheat (Triticum aestivumL.), glasshouse cucumber (Cucumis sativusL.), birch (Betula verrucosaEhrh.), lingonberry (Vaccinium vitis‐idaeaL.), Scots pine (Pinus silvestrisL.) and Norway spruce (Picea abies(L.) Karst.), The results were interpreted in terms of sigmoidal enzyme kinetics for allosteric regulation. Hill plots of the data gave straight lines at specific [K+]iintervals for the species. The slopes of the lines are the Hill coefficient, which could be regarded as a measure of the minimal number of allosteric sites. The Hill coefficient varied between ‐ 14.4 and ‐ 15.9. When divided by four, these values are fairly consistent with those in the literature. It is suggested that four active uptake sites interact with four groups of allosteric sites, each group containing four such sites, or that one active uptake site interacts with all the allosteric sites. Thus the results are evidence that the mechanism regulating K+uptake is basically similar for the investigated plants. It is the interval of [K+]imediating highly negatively cooperative allosteric regulation that differs among species. For some of the species,ndecreased from about 15 and approached unity at high [K+]ivalues. This may indicate that only few site...