Schnell K F, Besl E, Manz A
Pflugers Arch. 1978 Jun 21;375(1):87-95. doi: 10.1007/BF00584152.
The concentration dependence of the unidirectional chloride flux and the inhibition of the unidirectional chloride flux by sulfate were studied in human red cell ghosts. The concentration dependence of the unidirectional chloride flux and its inhibition by sulfate were asymmetric. The unidirectional chloride flux can be saturated from the inner and from the outer membrane surface. For the inner membrane surface, lower chloride half-saturation constants were obtained than for the outer membrane surface. The inhibition of the unidirectional chloride flux by sulfate is competitive. In contrast to the chloride half-saturation constants, the inhibition constants of sulfate for the inner membrane surface were higher than the inhibition constants of sulfate for the outher membrane surface. Either there are fixed anion binding sites at the inner and at the outer membrane surface which control the access of anions to a pore, or there is a mobile carrier which is in contact with both membrane surfaces. The asymmetry of the concentration response and of the inhibition of the unidirectional chloride flux suggest that the anion binding sites at the inner and at the outer membrane surface differ with respect to their affinities for chloride and for sulfate. Alternatively, the asymmetry of the chloride transport system could indicate an asymmetric distribution of a mobile anion carrier across the erythrocyte membrane.
在人红细胞血影中研究了单向氯离子通量的浓度依赖性以及硫酸盐对单向氯离子通量的抑制作用。单向氯离子通量的浓度依赖性及其受硫酸盐的抑制作用是不对称的。单向氯离子通量可从内膜表面和外膜表面达到饱和。对于内膜表面，获得的氯离子半饱和常数低于外膜表面。硫酸盐对单向氯离子通量的抑制是竞争性的。与氯离子半饱和常数相反，硫酸盐对内膜表面的抑制常数高于对内膜表面的抑制常数。要么在内膜表面和外膜表面存在固定的阴离子结合位点，控制阴离子进入孔道，要么存在与两个膜表面都接触的移动载体。浓度响应和单向氯离子通量抑制的不对称性表明，内膜表面和外膜表面的阴离子结合位点对氯离子和硫酸盐的亲和力不同。或者，氯离子转运系统的不对称性可能表明移动阴离子载体在红细胞膜上的不对称分布。
