Aszalos A, Damjanovich S, Gottesman M M
Biochemistry. 1986 Sep 23;25(19):5804-9. doi: 10.1021/bi00367a069.
Two independent lines of evidence were obtained indicating that microtubule depolymerization affects the functions and the physical state of membranes in intact Chinese hamster ovary cells. The first type of evidence was obtained by using the dye dihexyloxacarbocyanine iodide to measure membrane potential before and after treatment with several microtubule active agents. Microtubule depolymerization resulted in a decrease in cell fluorescence, whereas stabilization of microtubules with taxol resulted in an increase in cell fluorescence. These effects of the drugs were due to their interactions with microtubules and not to direct effects of the drugs on the plasma membranes for the following reasons: effects were time dependent and required entry into the cells as indicated by the lack of fluorescence change in a multi-drug-resistant mutant that does not accumulate antimicrotubule drugs and a colcemid-resistant tubulin mutant did not show these effects on cell fluorescence. Evidence for altered motional freedom of membrane proteins in the plasma membrane was obtained by using electron spin resonance analysis of maleimide spin probe labeled cells. This study showed that depolymerization of microtubules results in increased motional freedom of maleimide-labeled sulfhydryl group containing proteins. Taken together, these data argue that microtubules function in mammalian cells to regulate the physical state of membranes and modulate membrane potential generated across cell membranes.
获得了两条独立的证据线索，表明微管解聚影响完整的中国仓鼠卵巢细胞中膜的功能和物理状态。第一种证据是通过使用染料碘化二己基草氰来测量用几种微管活性剂处理前后的膜电位获得的。微管解聚导致细胞荧光降低，而用紫杉醇稳定微管则导致细胞荧光增加。这些药物的作用是由于它们与微管的相互作用，而不是药物对质膜的直接作用，原因如下：作用是时间依赖性的，并且需要进入细胞，这一点由不积累抗微管药物的多药耐药突变体中缺乏荧光变化所表明，而抗秋水仙酰胺的微管蛋白突变体对细胞荧光没有这些影响。通过对马来酰亚胺自旋探针标记的细胞进行电子自旋共振分析，获得了质膜中膜蛋白运动自由度改变的证据。这项研究表明，微管解聚导致马来酰亚胺标记的含巯基蛋白的运动自由度增加。综上所述，这些数据表明微管在哺乳动物细胞中发挥作用，以调节膜的物理状态并调节跨细胞膜产生的膜电位。
