Purchio A F, Erikson E, Erikson R L
Proc Natl Acad Sci U S A. 1977 Oct;74(10):4661-5. doi: 10.1073/pnas.74.10.4661.
Rabbit antiserum monospecific for an internal structural protein, p27, of avian sarcoma viruses (ASV) was found to immunoprecipitate polypeptides with molecular weights (Mr) of 180,000 and 76,000 from cell-free reticulocyte lysates programmed by ASV 35S RNA and also from lysates of ASV-infected cells. In addition, the Mr 180,000 protein was also precipitated by antiserum raised against virion DNA polymerase, suggesting that is a product of the two genes nearest the 5' end of virion 35S RNA. We have also investigated the ability of subgenomic portions of virion RNA to program cell-free protein synthesis. A 10-12S poly(A)-containing fragment of RNA from both nondefective and transformation-defective ASV directed the synthesis of a polypeptide of Mr 29,000 immunologically unrelated to the gs antigens; 20-24S poly(A)-containing RNA from nondefective ASV directed the synthesis of a polypeptide of Mr 60,000 not found when a similar RNA preparation from transformation-defective ASV was translated, suggesting that it is the product of the ASV src gene. These results indicate that internal initiation sites for protein synthesis exist on the 35S RNA genome.
发现对禽肉瘤病毒（ASV）的一种内部结构蛋白p27具有单特异性的兔抗血清，能从由ASV 35S RNA编程的无细胞网织红细胞裂解物以及ASV感染细胞的裂解物中免疫沉淀分子量（Mr）为180,000和76,000的多肽。此外，针对病毒体DNA聚合酶产生的抗血清也沉淀出了Mr 180,000的蛋白，这表明它是病毒体35S RNA 5'端附近两个基因的产物。我们还研究了病毒体RNA的亚基因组部分指导无细胞蛋白质合成的能力。来自非缺陷型和转化缺陷型ASV的一个含10 - 12S聚腺苷酸的RNA片段指导合成了一种Mr 29,000的多肽，该多肽在免疫上与gs抗原无关；来自非缺陷型ASV的含20 - 24S聚腺苷酸的RNA指导合成了一种Mr 60,000的多肽，而当翻译来自转化缺陷型ASV的类似RNA制剂时未发现这种多肽，这表明它是ASV src基因的产物。这些结果表明在35S RNA基因组上存在蛋白质合成的内部起始位点。
