Department of Botany and Zoology, Massey University, Palmerston North, New Zealand.
Plant Physiol. 1976 Jul;58(1):33-7. doi: 10.1104/pp.58.1.33.
Plasmalemma influx isotherms for K(+) were measured in the system I concentration range (0.01-0.32 mm), for barley (Hordeum vulgare L.) roots of varying internal K(+) concentration, and Km values for influx calculated. In plants grown for several days in CaSO(4) or in CaSO(4) plus KCl solutions, as well as in plants grown in CaSO(4) for several days and then rapidly loaded with KCl during a pretreatment period, Michaelis constant values were positively correlated with internal K(+) concentrations. Influx of K(+) is shown to be sigmoidally related to internal K(+) concentration and Hill plots of influx data give linear transformations with n = 4. This information is taken as support for an allosteric model for the regulation of K(+) influx in which the "carrier" is envisaged as possessing a single external binding site for K(+) as well as four internal sites for allosteric control of influx.
质膜流入等动力学曲线是在系统 I 浓度范围内(0.01-0.32mm)测量的,研究对象为不同内部 K+浓度的大麦(Hordeum vulgare L.)根,以及计算出的流入 Km 值。在 CaSO4 或 CaSO4 加 KCl 溶液中生长数天的植物,以及在 CaSO4 中生长数天然后在预处理期间快速加载 KCl 的植物中,米氏常数值与内部 K+浓度呈正相关。K+的流入被证明与内部 K+浓度呈“S”形相关,并且流入数据的希尔图给出了 n = 4 的线性变换。这些信息被视为对 K+流入调节的变构模型的支持,其中“载体”被设想为具有单个外部结合位点用于 K+,以及四个内部位点用于流入的变构控制。