de Jong A, Borstlap A C
Transport Physiology Research Group, Department of Plant Ecology and Evolutionary Biology, Utrecht University, Sorbonnelaan 16, NL-3584 CA Utrecht, The Netherlands.
J Exp Bot. 2000 Oct;51(351):1663-70. doi: 10.1093/jexbot/51.351.1663.
Transport of the amino acids L-valine, L-lysine, and L-glutamic acid and of sucrose was studied in plasma membrane vesicles isolated from developing cotyledons of pea (Pisum sativum L. cv. Marzia). The vesicles were obtained by aqueous polymer two-phase partitioning of a microsomal fraction and the uptake was determined after the imposition of a H(+)-gradient (DeltapH, inside alkaline) and/or an electrical gradient (Deltapsi, inside negative) across the vesicle membrane. In the absence of gradients, a distinct, time-dependent uptake of L-valine was measured, which could be enhanced about 2-fold by the imposition of DeltapH. The imposition of Deltapsi stimulated the influx of valine by 20%, both in the absence and in the presence of DeltapH. Uptake of L-lysine was more strongly stimulated by Deltapsi than by DeltapH, and its DeltapH-dependent uptake was enhanced about 6-fold by the simultaneous imposition of Deltapsi. In the absence of gradients the uptake of L-glutamic acid was about 2-fold higher than that of L-valine, but it was not detectably affected by DeltapH or Deltapsi. Although the transport of sucrose was very low, a stimulating effect of DeltapH could be clearly demonstrated. The results lend further support to the contention that during seed development cotyledonary cells employ H(+)-symporters for the active uptake of sucrose and amino acids.
在从豌豆（Pisum sativum L. cv. Marzia）发育中的子叶分离出的质膜囊泡中，研究了氨基酸L-缬氨酸、L-赖氨酸和L-谷氨酸以及蔗糖的转运。通过对微粒体部分进行水相聚合物双相分配获得囊泡，并在跨囊泡膜施加H⁺梯度（ΔpH，内部呈碱性）和/或电势梯度（Δψ，内部为负）后测定摄取量。在没有梯度的情况下，测量到L-缬氨酸有明显的、随时间变化的摄取，施加ΔpH可使其增加约2倍。无论是否存在ΔpH，施加Δψ均可使缬氨酸的流入量增加20%。L-赖氨酸的摄取受Δψ的刺激比受ΔpH的刺激更强，同时施加Δψ可使其依赖于ΔpH的摄取增加约6倍。在没有梯度的情况下，L-谷氨酸的摄取量比L-缬氨酸高约2倍，但它不受ΔpH或Δψ的明显影响。尽管蔗糖的转运非常低，但ΔpH的刺激作用可以清楚地证明。这些结果进一步支持了这样的观点，即在种子发育过程中，子叶细胞利用H⁺同向转运体来主动摄取蔗糖和氨基酸。
