Smith G H, Wivel N A
J Virol. 1973 Apr;11(4):575-84. doi: 10.1128/JVI.11.4.575-584.1973.
A rapid method for the isolation of intracytoplasmic A particles, the putative intracellular nucleoprotein cores of mouse mammary tumor virus (MTV), is presented. Spontaneous C3H/He mouse mammary tumors and transplantable mouse Leydig cell tumor were used as source material. Large aggregations of intracytoplasmic A particles were separated from cellular contaminants on discontinuous sucrose gradients and subsequently further purified by isopycnic banding in linear sucrose gradients. The purified particles were solubilized in sodium dodecyl sulfate, and the structural proteins were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Purified mouse mammary tumor virions were solubilized, and their proteins were analyzed in the same way. Comparison of co-electrophoretic gels indicated a lack of correlation in the molecular size of the major structural proteins in intracytoplasmic A particles and MTV. The three major proteins of the A particles were calculated to be 80,000; 35,000; and 20,000 daltons. Five major polyacrylamide gel electrophoresis bands were obtained with purified MTV; these were 90,000; 69,000; 55,000; 37,000; and 27,500 daltons. These figures showed good correlation with those published for MTV by Nowinski et al. These results suggest the need for the reexamination of the current tenet that intracytoplasmic particles represent intracellular MTV nucleoprotein cores.
本文介绍了一种快速分离胞质A颗粒的方法，胞质A颗粒被认为是小鼠乳腺肿瘤病毒（MTV）的细胞内核蛋白核心。自发的C3H/He小鼠乳腺肿瘤和可移植的小鼠睾丸间质细胞瘤被用作原材料。通过不连续蔗糖梯度从细胞污染物中分离出大量聚集的胞质A颗粒，随后通过线性蔗糖梯度中的等密度区带进一步纯化。将纯化的颗粒溶解在十二烷基硫酸钠中，并通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳分析其结构蛋白。将纯化的小鼠乳腺肿瘤病毒粒子溶解，并以相同的方式分析其蛋白质。共电泳凝胶的比较表明，胞质A颗粒和MTV中主要结构蛋白的分子大小缺乏相关性。计算得出A颗粒的三种主要蛋白质的分子量分别为80,000；35,000；和20,000道尔顿。纯化的MTV获得了五条主要的聚丙烯酰胺凝胶电泳带；这些带的分子量分别为90,000；69,000；55,000；37,000；和27,500道尔顿。这些数据与Nowinski等人发表的关于MTV的数据具有良好的相关性。这些结果表明，有必要重新审视当前关于胞质颗粒代表细胞内MTV核蛋白核心的原则。
