Central Research and Development Department, E. I. du Pont de Nemours and Company, Experimental Station, Wilmington, Delaware 19898.
Plant Physiol. 1985 Jul;78(3):649-51. doi: 10.1104/pp.78.3.649.
Previous studies with isolated soybean cotyledon protoplasts revealed the presence of a saturable, simple diffusion, and nonsaturating carrier-mediated uptake of sucrose into soybean cotyledon cells. A proton/sucrose cotransport may be involved in the saturable sucrose uptake (Lin et al. 1984 Plant Physiol 75: 936-940 and Schmitt et al. 1984 Plant Physiol 75: 941-946). In this study, we investigated the linear sucrose uptake mechanism by treating isolated protoplasts with 15 micromolar p-trifluoromethoxy-carbonylcyanide phenylhydrazone (FCCP) or 100 micromolar p-chloromecuribenzenesulfonic acid to eliminate the saturable uptake. We found: (a) increasing external pH decreases the linear sucrose uptake; (b) fusicoccin at 20 micromolar stimulates and FCCP at 15 micromolar inhibits this linear sucrose uptake; and (c) the ratio of the initial influx of proton to sucrose is close to one in both saturable and nondiffusive linear (difference between the total linear and diffusive components) uptakes. The results suggest that a proton/sucrose cotransport is also involved in the nondiffusive linear sucrose uptake into soybean cotyledon cells.
先前对分离的大豆子叶原生质体的研究表明，蔗糖进入大豆子叶细胞存在可饱和的、单纯扩散的和非饱和的载体介导的摄取。质子/蔗糖协同转运可能参与可饱和的蔗糖摄取（Lin 等人，1984 年《植物生理学》75:936-940 和 Schmitt 等人，1984 年《植物生理学》75:941-946）。在这项研究中，我们通过用 15 微摩尔对三氟甲氧基羰基氰苯腙（FCCP）或 100 微摩尔对氯汞苯甲酸处理分离的原生质体来研究线性蔗糖摄取机制，以消除可饱和的摄取。我们发现：（a）增加外部 pH 会降低线性蔗糖摄取；（b）20 微摩尔的 Fusicoccin 刺激而 15 微摩尔的 FCCP 抑制这种线性蔗糖摄取；（c）在可饱和和非扩散线性（总线性和扩散成分之间的差异）摄取中，质子到蔗糖的初始内流比接近 1。结果表明，质子/蔗糖协同转运也参与了大豆子叶细胞中非扩散线性蔗糖的摄取。
