Changes of H^+-pumping activity of the vesicles prepared from plant roots grown under salt stress

在Ca^<2+>饥饿时，黄瓜根系的质子分泌显著减少. Ca^2+饥饿根中囊泡的质子转运速率被抑制到对照根中囊泡的一半以下。与囊泡相关的K^+-Mg^<2+>-ATP酶活性在Ca^<2+>缺乏时显著降低。从黄瓜根质膜制备的部分去脂ATP酶与大豆卵磷脂结合。对照根的ATP酶活性明显高于Ca^2+饥饿根。从对照根中制备的部分脂质耗尽的ATP酶最大活化所需的asolectin的量远低于从Ca^2+饥饿根中制备的asolectin的量。ATP酶与磷脂结合功能的降低可能是Ca^<2+>缺乏引起的黄瓜根细胞膜生理损伤之一。大麦囊泡的H^+转运活性 ...更多信息 200 mM NaCl胁迫下，根数增加。在蛋白质合成抑制剂的存在下，这种增加被抑制。与H^+-转运活性相关的膜泡的性质表明，膜是液泡膜起源的。对与H^+转运活性相关的囊泡进行密度梯度离心，结果显示没有可检测到的差异，对照和NaCl胁迫根的囊泡的H^+转运活性的ATP Km值相同。这些结果表明，螯合的盐进入液泡进行的质子泵增加与液泡。大麦鲁什经1 mM AlCl_3处理后，质子的排出量明显减少，这可能是大麦对盐胁迫的一种适应机制。在pH6.5时，100 M AlCl_3对膜囊泡的H^+转运活性的抑制约为50%，但在pH7.5时，抑制仅为10%。柠檬酸可有效地恢复与Al引起的囊泡H^+转运活性相关的ATP的Vmax和Km值。结果表明，铝对植物根系的毒害作用机制之一是抑制了根系的H^+运输活性，进而抑制了根系的质子排出。少

Proton extrusion from cucumber roots decrease markedly during Ca^<2+> starvation. The proton transport rate of the vesicles from Ca^<2+>-starved root was repressed to less than half of the vesicles from control roots. K^+-Mg^<2+>-ATPase activity associated with the vesicles decreased markedly by Ca^<2+> deficiency. Partially lipid-depleted ATPase prepared from plasma membrane of cucumber roots reassociated with asolection, soybean lecitin. The activity of reassociated ATPase obtained from the control roots was apparently higher than the activity of Ca^<2+>-starved roots. The amount of asolectin required for maximum activation of the partially lipid-depleted ATPase prepared from control roots was much lower than that prepared from Ca^<2+>-starved roots. A decrease in the functional association of ATPase with phospholipids might be one of the physiological injuries in root cell membranes of cucumber caused by Ca^<2+> deficiency.H^+-transport activity of the vesicles prepared from barley … More roots increased with 200 mM NaCl stress. This increase was suppressed in the presence of inhibitors of protein synthesis. The properties of the membrane vesicles associated with H^+-transport activity suggested that membrane was tonoplast origin. The density gradient centrifugation of vesicles associated with H^+-transport activity showed no detectable difference and Km values for ATP of the H^+-transport activity of vesicles from control and NaCl-stressed roots were the same. These results suggest that the sequestration of the salts into vacuoles is carried out by the increased proton pump associated with the tonoplast. This could be an adaptive mechanism of barley against salt stress.The extrusion of protons from barley roos decreased markedly after the treatment with 1 mM AlCl_3. H^+-transport activity of the membrane vesicles was inhibited by approximately 50% in the presence of 100 M AlCl_3 at pH 6.5 but the inhibition was only 10% at pH 7.5 . The values of Vmax and Km for ATP related to the H^+-transport activity of the vesicles due to Al was effectively restored by citric acid. The results suggest that one of the mechanism of Al toxicity in plant roots is the inhibition of the H^+ transport activity which in turn leads to the inhibition of proton extrusion from the roots. Less