Koizumi K, Kano-Tanaka K, Shimizu S, Nishida K, Yamanaka N, Ota K
Biochim Biophys Acta. 1980 Aug 11;619(2):344-52. doi: 10.1016/0005-2760(80)90082-x.
Plasma membranes were isolated from normal thymocytes of Wistar-King-A rats and from Moloney virus-induced rat thymic leukemias (RML11 and RML30 cells) using a simplified method developed by us. All the isolated plasma membranes were electron-microscopically pure and enriched in the specific activities of (Na+ + K+)-ATPase, Mg2+-ATPase and 5'-nucleotidase in comparison with those of the corresponding whole cell homogenates. These plasma membranes as well as the original cells were analyzed for phopholipid composition and contents of phospholipid, cholesterol and plasmalogen. There was no difference in the phospholipid composition among the three plasma membranes. However, all the plasma membranes were deficient in sphingomyelin, namely, 1.8% for the normal thymocytes, 2.2% for the RML11 cells and 1.9% for the RML30 cells as percentage of the total phospholipid phosphorus. The contents of phospholipid (mumol per mg protein), cholesterol (mumol per mg protein) and plasmalogen (mol% to phospholipid) of the plasma membranes from both lines of malignant cells were lower than those of the normal thymocyte membranes. The molar ratio of cholesterol to phospholipid of the malignant cell membranes was also lower than that of the normal membranes, because in the former membranes the degree of decrease in the cholesterol content was higher than that in phospholipid content.
采用我们改进的简化方法，从Wistar-King-A大鼠的正常胸腺细胞以及莫洛尼病毒诱导的大鼠胸腺白血病细胞（RML11和RML30细胞）中分离出质膜。与相应的全细胞匀浆相比，所有分离出的质膜在电子显微镜下均纯净，且（Na⁺ + K⁺）-ATP酶、Mg²⁺-ATP酶和5'-核苷酸酶的比活性较高。对这些质膜以及原始细胞进行了磷脂组成分析，并测定了磷脂、胆固醇和缩醛磷脂的含量。三种质膜的磷脂组成没有差异。然而，所有质膜中的鞘磷脂均缺乏，即正常胸腺细胞中为总磷脂磷的1.8%，RML11细胞中为2.2%，RML30细胞中为1.9%。两种恶性细胞系的质膜中磷脂（每毫克蛋白质的微摩尔数）、胆固醇（每毫克蛋白质的微摩尔数）和缩醛磷脂（相对于磷脂的摩尔百分比）的含量均低于正常胸腺细胞质膜。恶性细胞质膜中胆固醇与磷脂的摩尔比也低于正常质膜，因为在前者的质膜中，胆固醇含量的降低程度高于磷脂含量。
