Voĭtsitskiĭ V M, Fedorov A N, Kurskiĭ M D, Kucherenko N E, Tugaĭ V A
Biokhimiia. 1988 Sep;53(9):1427-32.
The Ca2+ permeability of proteoliposomes containing Ca2+-ATPase of sarcoplasmic reticulum and its hydrophobic fragment was investigated, using the method of synthetic penetrant ions and the radioisotopic method. The former method was used to determine the diffusional membrane potential formed by Ca2+ concentration gradient. It was demonstrated that Ca2+-ATPase, whose active center is oriented outside, has and asymmetric conductivity, i. e., it facilitates the rapid efflux of Ca2+ from proteoliposomes. This efflux is stimulated by the membrane potential positive inside. The hydrophobic fragment of Ca2+-ATPase forms a Ca2+-channel with a high conductivity for Ca2+. This channel is responsible for the Ca2+ efflux from sarcoplasmic reticulum.
采用合成渗透离子法和放射性同位素法，研究了含有肌浆网Ca2 + -ATP酶及其疏水片段的蛋白脂质体的Ca2 +渗透性。前一种方法用于测定由Ca2 +浓度梯度形成的扩散膜电位。结果表明，活性中心向外的Ca2 + -ATP酶具有不对称导电性，即它促进Ca2 +从蛋白脂质体快速外流。这种外流受到膜内正电位的刺激。Ca2 + -ATP酶的疏水片段形成了一个对Ca2 +具有高导电性的Ca2 +通道。该通道负责Ca2 +从肌浆网的外流。
