Gimble J M, Waisman D M, Gustin M, Goodman D B, Rasmussen H
J Biol Chem. 1982 Sep 25;257(18):10781-8.
Previous observations on the effects of permeant anions on ATP-dependent calcium transport in inside-out vesicles prepared from human erythrocytes suggested that the calcium pump is electrogenic, generating a positive interior membrane potential. The present work demonstrates the development of a positive interior membrane potential across inside-out vesicle membranes during calcium transport in the absence of permeant anions. Several membrane potential probes, 1-anilino-8-naphthalenesulfonate, 3,3'-dipropylthiodicarbocyanine iodide, and an electron paramagnetic resonant triphenylphosphonium derivative, provide qualitative evidence for the development of a membrane potential. Moreover, a number of parallels are observed between the changes in the membrane potential measured by the probes and calcium transport. These include enhancement by calmodulin, time course of change, similar kinetic properties, and the requirement for intact vesicle membranes. Quantitative measurements of the membrane potential shows a positive interior membrane potential of 26-37 mV using radiolabeled permeant anion distribution and 38-57 mV using 3,3'-dipropylthiodicarbocyanine iodide fluorescence changes. These membrane potentials are of a similar magnitude to those reported for the sarcoplasmic reticulum calcium pump (Zimniak, P., and Racker, E. (1978). J. Biol. Chem. 253, 4631-4637).
先前对通透阴离子对人红细胞制备的内翻囊泡中ATP依赖的钙转运影响的观察表明，钙泵是生电的，能产生正的内膜电位。目前的工作证明了在没有通透阴离子的情况下，钙转运过程中内翻囊泡膜上会产生正的内膜电位。几种膜电位探针，1-苯胺基-8-萘磺酸盐、3,3'-二丙基硫代二羰花青碘化物和一种电子顺磁共振三苯基鏻衍生物，为膜电位的产生提供了定性证据。此外，在探针测量的膜电位变化和钙转运之间观察到许多相似之处。这些包括钙调蛋白的增强作用、变化的时间进程、相似的动力学性质以及对完整囊泡膜的要求。使用放射性标记的通透阴离子分布进行的膜电位定量测量显示，内膜电位为26 - 37 mV，而使用3,3'-二丙基硫代二羰花青碘化物荧光变化测量得到的内膜电位为38 - 57 mV。这些膜电位的大小与肌浆网钙泵报道的膜电位大小相似（齐米亚克，P.，和拉克尔，E.（1978年）。《生物化学杂志》253，4631 - 4637）。
