Takeya T, Hanafusa H, Junghans R P, Ju G, Skalka A M
Mol Cell Biol. 1981 Nov;1(11):1024-37. doi: 10.1128/mcb.1.11.1024-1037.1981.
Recovered avian sarcoma viruses are recombinants between transformation-defective mutants of Rous sarcoma virus and the chicken cellular gene homologous to the src gene of Rous sarcoma virus. We have constructed and analyzed molecular clones of viral deoxyribonucleic acid from recovered avian sarcoma virus and its transformation-competent progenitor, the Schmidt-Ruppin A strain of Rous sarcoma virus. A 2.0-megadalton EcoRI fragment containing the entire src gene from each of these clones was subcloned and characterized. These fragments were also used as probes to isolate recombinant phage clones containing the cellular counterpart of the viral src gene, termed cellular src, from a lambda library of chicken deoxyribonucleic acid. The structure of cellular src was analyzed by restriction endonuclease mapping and electron microscopy. Restriction endonuclease mapping revealed extensive similarity between the src regions of Rous sarcoma virus and recovered avian sarcoma virus, but striking differences between the viral src's and cellular src. Electron microscopic analysis of heteroduplexes between recovered virus src and cellular src revealed a 1.8-kilobase region of homology. In the cellular gene, the homologous region was interrupted by seven nonhomologous regions which we interpret to be intervening sequences. We estimate the minimum length of cellular src to be about 7.2 kilobases. These findings have implications concerning the mechanism of formation of recovered virus src and possibly other cell-derived retrovirus transforming genes.
恢复的禽肉瘤病毒是劳斯肉瘤病毒的转化缺陷型突变体与鸡细胞中与劳斯肉瘤病毒src基因同源的基因之间的重组体。我们构建并分析了来自恢复的禽肉瘤病毒及其具有转化能力的祖代——劳斯肉瘤病毒施密特-鲁平A株的病毒脱氧核糖核酸分子克隆。从这些克隆中分别取出包含整个src基因的2.0兆道尔顿EcoRI片段进行亚克隆和鉴定。这些片段还被用作探针，从鸡脱氧核糖核酸的λ文库中分离出含有病毒src基因细胞对应物（称为细胞src）的重组噬菌体克隆。通过限制性内切酶图谱分析和电子显微镜对细胞src的结构进行了分析。限制性内切酶图谱分析显示，劳斯肉瘤病毒和恢复的禽肉瘤病毒的src区域之间有广泛的相似性，但病毒src与细胞src之间存在显著差异。对恢复病毒src与细胞src之间的异源双链体进行电子显微镜分析，发现了一个1.8千碱基的同源区域。在细胞基因中，同源区域被七个非同源区域打断，我们将这些区域解释为间隔序列。我们估计细胞src的最小长度约为7.2千碱基。这些发现对恢复病毒src以及可能其他细胞来源的逆转录病毒转化基因的形成机制具有启示意义。
