Pipas J M, Peden K W, Nathans D
Mol Cell Biol. 1983 Feb;3(2):203-13. doi: 10.1128/mcb.3.2.203-213.1983.
A series of mutants of simian virus 40 has been constructed with deletions in the coding sequence for large T antigen. Nucleotide sequence analysis indicates that 4 mutants have in-phase and 11 have out-of-phase deletions. Mutant DNAs were assayed for the following activities: the ability to form plaques, the ability to produce T antigen as scored by indirect immunofluorescence, viral DNA replication, and morphological transformation of rat cells. Two viable mutants were found, and these had deletions confined to the carboxyl terminus of T antigen. Only those mutants coding for polypeptides greater than 40% of the length of wildtype T antigen produced detectable nuclear fluorescence. The two viable mutants with deletions in the carboxyl terminus of the protein retained the ability both to replicate their DNA, although at a reduced level, and to transform nonpermissive cells. Mutants with sequence changes that result in the loss of more than 117 amino acids from the carboxyl terminus were not viable and were also defective in the DNA replication and transformation functions of T antigen, although several produced detectable nuclear fluorescence. These functions were also sensitive to the removal of amino acids near the amino terminus and in the middle of the protein.
已构建了一系列猴病毒40的突变体，其大T抗原编码序列存在缺失。核苷酸序列分析表明，4个突变体具有同相位缺失，11个具有异相位缺失。对突变DNA进行了以下活性检测：形成噬菌斑的能力、通过间接免疫荧光测定产生T抗原的能力、病毒DNA复制以及大鼠细胞的形态转化。发现了两个存活的突变体，它们的缺失局限于T抗原的羧基末端。只有那些编码的多肽长度大于野生型T抗原长度40%的突变体产生可检测到的核荧光。蛋白质羧基末端有缺失的两个存活突变体保留了复制其DNA的能力，尽管水平有所降低，并且能够转化非允许细胞。羧基末端序列变化导致缺失超过117个氨基酸的突变体无法存活，并且在T抗原的DNA复制和转化功能方面也存在缺陷，尽管有几个产生了可检测到的核荧光。这些功能对蛋白质氨基末端附近和中间氨基酸的去除也很敏感。
