Wang Y L, Lanni F, McNeil P L, Ware B R, Taylor D L
Proc Natl Acad Sci U S A. 1982 Aug;79(15):4660-4. doi: 10.1073/pnas.79.15.4660.
We have combined fluorescent analogue cytochemistry with fluorescence photobleaching recovery to measure the mobility of fluorescently labeled actin and other labeled test proteins microinjected into living amoebae. Bovine serum albumin, ovalbumin, and ribonuclease A have a cytoplasmic mobility, expressed as a diffusion coefficient, that is 1/2 to 1/3 of that observed in aqueous solution; 90% of the actin has a mobility 1/2 to 1/8 of that of G-actin in aqueous solution, and approximately equal to 10% of the actin has a mobility comparable to that of F-actin in aqueous solution. Therefore, no more than 10% of the actin in the cytoplasm of amoebae can exist as static filaments. Microinjection of phalloidin decreases the diffusion coefficient of the mobile component of cytoplasmic actin, and it also increases the low-mobility fraction to 50% but has no effect on the mobility of labeled ovalbumin. By comparing the mobility of actin in different parts of amoebae and by separating cytoplasm from plasmalemma-ectoplasm, we found the low-mobility fraction of actin to be enriched in the tail, along the plasmalemma-ectoplasm, and in contracted cytoplasm.
我们将荧光类似物细胞化学与荧光光漂白恢复技术相结合，以测量微注射到活变形虫中的荧光标记肌动蛋白和其他标记测试蛋白的流动性。牛血清白蛋白、卵清蛋白和核糖核酸酶A在细胞质中的流动性（以扩散系数表示）是在水溶液中观察到的流动性的1/2至1/3；90%的肌动蛋白的流动性是其在水溶液中G-肌动蛋白流动性的1/2至1/8，约10%的肌动蛋白的流动性与水溶液中F-肌动蛋白的流动性相当。因此，变形虫细胞质中不超过10%的肌动蛋白可以以静态细丝的形式存在。微注射鬼笔环肽会降低细胞质肌动蛋白可移动成分的扩散系数，还会将低流动性部分增加到50%，但对标记卵清蛋白的流动性没有影响。通过比较变形虫不同部位肌动蛋白的流动性，并将细胞质与质膜-外质分离，我们发现肌动蛋白的低流动性部分在尾部、沿质膜-外质以及收缩的细胞质中富集。
