Oskarsson M K, Long C W, Robey W G, Scherer M A, Vande Woude G F
J Virol. 1977 Jul;23(1):196-204. doi: 10.1128/JVI.23.1.196-204.1977.
The pP60gag polyprotein of the feline leukemia virus pseudotype of m1 Moloney murine sarcoma virus [m1MSV(FeLV)] was previously shown to be MSV specific and to contain murine p30 and smaller structural polypeptides. This protein was detected in m1MSV-transformed cells, and in pulse-chase studies it was found to be stable. In this study virion P60 was shown to contain murine pp12, to be phosphorylated, and to bind to nucleic acids. 32P-labeled m1MSV[FeLV) was fractionated by guanidine agarose chromatography and analyzed by gel electrophoresis. Both P60 and pp12 were found to be the major phosphoproteins, phosphorylated in both serine and threonine residues. Virion P60 bound preferentially to single-stranded DNA and RNA in a competition filter binding assay, using 125I-labeled single-stranded calf thymus DNA and various unlabeled nucleic acids. Similar phosphorylation and DNA binding properties were demonstrated for cellular P60. Thus, immunoprecipitation of cellular extracts showed that P60 was phosphorylated in both producer and nonproducer transformed cells, indicating that phosphorylation occurs independently of virus assembly. Moreover, P60 from cytoplasmic extracts was retained on single-stranded DNA-Sepharose columns, demonstrating that cellular P60 binds to DNA.
莫洛尼氏鼠肉瘤病毒（m1MSV）的猫白血病病毒假型的pP60gag多聚蛋白此前已被证明具有MSV特异性，且包含鼠源p30和较小的结构多肽。该蛋白在m1MSV转化的细胞中被检测到，并且在脉冲追踪研究中发现其是稳定的。在本研究中，病毒粒子P60被证明含有鼠源pp12，可被磷酸化，并能与核酸结合。用胍琼脂糖层析法对32P标记的m1MSV[FeLV]进行分离，并通过凝胶电泳进行分析。发现P60和pp12都是主要的磷蛋白，在丝氨酸和苏氨酸残基上均被磷酸化。在竞争滤膜结合试验中，使用125I标记的单链小牛胸腺DNA和各种未标记的核酸，病毒粒子P60优先与单链DNA和RNA结合。细胞P60也表现出类似的磷酸化和DNA结合特性。因此，细胞提取物的免疫沉淀显示，P60在产生病毒和不产生病毒的转化细胞中均被磷酸化，这表明磷酸化的发生与病毒组装无关。此外，细胞质提取物中的P60保留在单链DNA-琼脂糖柱上，表明细胞P60能与DNA结合。
