A model for proton and potassium co-transport during the uptake of glutamine and sucrose by tomato internode disks
A model for proton and potassium co-transport during the uptake of glutamine and sucrose by tomato internode disks
复制标题
番茄节间盘吸收谷氨酰胺和蔗糖过程中质子和钾共转运的模型
作者：
A. Bel;A. V. Erven
番茄（Lycopersicon esculentum）的节间盘。摇钱树)在谷氨酰胺和蔗糖溶液中摇晃。在低外部pH（<±5.5）下，这些物质的摄取伴随着K+外排，在高pH（>±5.5）下伴随着K+内流。低浓度的外部K+ (2 mmol l-1)刺激谷氨酰胺的吸收，高浓度K+ (20 mmol l-1)的供应强烈抑制谷氨酰胺的吸收。K+的作用在高ph值时尤为明显。光照条件下添加CCCP使谷氨酰胺的吸收降低到与黑暗条件下相同的水平，并使与吸收相一致的K+通量停止。提出了一个模型，其中K+在膜上的运动与共输运有关，取决于膜电位和K+的能势。
Internode disks of tomato (Lycopersicon esculentum cv. Moneymaker) were shaken in glutamine and sucrose solutions. At low external pH (<±5.5), the uptake of these substances was accompanied with K+ efflux, at high pH (>±5.5) with K+ influx. Low concentrations of external K+ (2 mmol l-1) stimulated the uptake of glutamine, which was strongly inhibited by the supply of high K+ concentrations (20 mmol l-1). The effect of K+ was particularly pronounced at high pH-values. Addition of CCCP in light reduced the uptake of glutamine to the same level as in the dark, and stopped the K+ fluxes which coincided with the uptake. A model is presented wherein the movements of K+ across the membrane are related to co-transport, depending on the membrane potential and the Nernst potential of K+.