Lopez S, Bell J R, Strauss E G, Strauss J H
Virology. 1985 Mar;141(2):235-47. doi: 10.1016/0042-6822(85)90254-5.
A dodecapeptide containing the sequence of the C terminus of the nonstructural polyprotein of Sindbis virus has been synthesized and used to immunize rabbits. The antisera obtained precipitated polypeptides from cells infected with the HR strains of Sindbis or with temperature-sensitive mutants ts11 or ts18. Four different polypeptides, having apparent molecular weights of approximately 250,000, 220,000, 155,000, and 72,000, were immunoprecipitated by the antipeptide antiserum. The largest of these polypeptides is sufficiently large to represent a polyprotein translated from the entire nonstructural region of the genome. These data suggest that nsP4 of molecular weight 72,000 is produced by translation of the entire nonstructural region of the genome, which requires readthrough of an opal termination codon immediately upstream of nsP4, followed by post-translational cleavage of this polyprotein. The amounts of nsP4 and its precursors found in infected cells are small relative to the amounts of other nonstructural proteins present, as would be expected if readthrough of a termination codon is required. In addition, the relative amounts of nsP4 and of its precursors differ in HR-infected or ts mutant-infected cells and differ with temperature of infection, suggesting that temperature of infection or ts lesions affect translation and processing of the precursor polyprotein.
一种含有辛德毕斯病毒非结构多聚蛋白C末端序列的十二肽已被合成，并用于免疫兔子。所获得的抗血清能沉淀来自感染辛德毕斯病毒HR株或温度敏感突变体ts11或ts18的细胞中的多肽。抗肽抗血清免疫沉淀出四种不同的多肽，其表观分子量约为250,000、220,000、155,000和72,000。这些多肽中最大的一个足够大，足以代表从基因组的整个非结构区域翻译而来的多聚蛋白。这些数据表明，分子量为72,000的nsP4是通过基因组整个非结构区域的翻译产生的，这需要在nsP4上游紧邻的一个乳白终止密码子处发生通读，随后对该多聚蛋白进行翻译后切割。如果需要终止密码子的通读，那么在感染细胞中发现的nsP4及其前体的量相对于其他非结构蛋白的量来说是少的，这是预期的。此外，nsP4及其前体的相对量在HR感染或ts突变体感染的细胞中不同，并且随感染温度而不同，这表明感染温度或ts损伤会影响前体多聚蛋白的翻译和加工。
