Bradac J, Hunter E
Virology. 1984 Oct 30;138(2):260-75. doi: 10.1016/0042-6822(84)90350-7.
Mason-Pfizer monkey virus (M-PMV), the prototype D-type retrovirus, differs from the mammalian C-type retroviruses by preassembling core structures in the cytoplasm of infected cells during morphogenesis. Studies that define the protein composition of M-PMV virions and identify two gag-related polyprotein precursors in M-PMV infected cells are reported. The polyprotein precursor to the internal structural (gag) proteins of M-PMV was identified by immunoprecipitation from lysates of pulse-labeled, virus-infected cells with an antiserum to the major structural protein, p27. Tryptic peptide-mapping experiments have shown that this precursor (Pr78) is cleaved to yield five virion structural polypeptides--p27, pp16, p14, p12, and p10. The pp16 polypeptide represents an additional gag-gene encoded polypeptide, not described previously; it is a phosphoprotein and present in virions in a number of forms. A second gag-related polyprotein precursor, P95, is also present in infected cells although in smaller amounts. This nonglycosylated polypeptide contains all of the leucine-containing tryptic peptides of Pr78 plus three others. Studies of the rate of synthesis and half-life of this protein argue against it being the major gag-gene precursor polypeptide. The possibility that it represents a precursor to the viral protease is discussed.
梅森- Pfizer猴病毒（M-PMV）是D型逆转录病毒的原型，在形态发生过程中，它通过在受感染细胞的细胞质中预先组装核心结构，与哺乳动物C型逆转录病毒不同。本文报道了确定M-PMV病毒粒子蛋白质组成并鉴定M-PMV感染细胞中两种与gag相关的多蛋白前体的研究。通过用针对主要结构蛋白p27的抗血清对脉冲标记的病毒感染细胞裂解物进行免疫沉淀，鉴定出M-PMV内部结构（gag）蛋白的多蛋白前体。胰蛋白酶肽图谱实验表明，该前体（Pr78）被切割产生五种病毒粒子结构多肽——p27、pp16、p14、p12和p10。pp16多肽代表一种以前未描述过的额外的gag基因编码多肽；它是一种磷蛋白，以多种形式存在于病毒粒子中。第二种与gag相关的多蛋白前体P95也存在于受感染细胞中，但其含量较少。这种非糖基化多肽包含Pr78所有含亮氨酸的胰蛋白酶肽以及另外三种。对该蛋白合成速率和半衰期的研究表明它不是主要的gag基因前体多肽。文中讨论了它代表病毒蛋白酶前体的可能性。
