质子/硫酸盐共转运及其在浮萍 G1 中的动力学证据。

Evidence for proton/sulfate cotransport and its kinetics inLemna gibba G1.

机构信息

Institut für Botanik der Technischen Hochschule, Schnittspahnstrasse 3, D-6100, Darmstadt, Germany.

出版信息

Planta. 1984 Jan;161(1):53-60. doi: 10.1007/BF00951460.

Abstract

Sulfate uptake into duckweed (Lemna gibba G1) was studied by means of [(35)S]sulfate influx and measurements of electrical membrane potential. Uptake was strongly regulated by the intracellular content of soluble sulfate. At the onset of sulfate uptake the membrane potential was transiently depolarized. Fusicoccin stimulated uptake up to 165% of the control even at pH 8. It is suggested that sulfate uptake is energized in the whole pH range by a 3H(+)/sulfate cotransport mechanism. Kinetics of sulfate uptake and sulfate-induced membrane depolarization in the concentration range of 5 μM to 1 mM sulfate at pH 5.7 was best described by two Michaelis-Menten terms without any linear component. The second system had a lower affinity for sulfate and was fully active only at sufficiently high proton concentrations.

摘要

采用 [(35)S]硫酸盐内流和测量膜电位的方法研究了浮萍（浮萍 G1）对硫酸盐的摄取。硫酸盐的摄取受到细胞内可溶性硫酸盐含量的强烈调节。硫酸盐摄取开始时，膜电位会短暂去极化。即使在 pH 值为 8 时，红景天也能刺激摄取，使其达到对照的 165%。这表明硫酸盐摄取在整个 pH 范围内由 3H(+) /硫酸盐共转运机制提供能量。在 pH 值为 5.7 时，硫酸盐浓度范围为 5 μM 至 1 mM 的硫酸盐摄取动力学和硫酸盐诱导的膜去极化最好用两个米氏-门捷列夫项来描述，没有任何线性成分。第二个系统对硫酸盐的亲和力较低，只有在足够高的质子浓度下才能完全激活。