Multiple, distinct trans-activation functions are encoded by the simian virus 40 large T and small t antigens, only some of which require the 82-residue amino-terminal common domain.
Multiple, distinct trans-activation functions are encoded by the simian virus 40 large T and small t antigens, only some of which require the 82-residue amino-terminal common domain.
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猿猴病毒 40 个大 T 和小 t 抗原编码多种不同的反式激活功能，只有其中一些需要 82 个残基的氨基末端共同结构域。
DOI：
10.1128/jvi.67.12.7684-7689.1993
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发表时间：
1993
影响因子：
5.4
通讯作者：
Loeken,MR
中科院分区：
文献类型：
--
作者：
Loeken,MR
猿猴病毒 40 (SV40) 小 t 和大 T 抗原均可反式激活腺病毒 (Ad) E2A 和 Ad VA-I 启动子。大T和小t的前82个氨基酸是相同的。然而，残基 1 和 82 之间的大 T-小 t 共同结构域不反式激活，表明大 T 和小 t 各自编码单独的反式激活功能。为了确定 E2A 启动子反式激活所需的大 T 或小 t 独特结构域是否足以实现此活性，我们使用了分别编码大 T 和小 t 的共同和独特结构域的表达质粒。大T独特结构域表达质粒的共转染有效地反式激活了E2A启动子。大T的最佳反式激活需要结合细胞蛋白的基序，例如位于大T独特结构域中的视网膜母细胞瘤基因产物，以及该基序之外的其他大T结构。相反，小的 t 独特结构域不会反式激活 E2A 启动子。利用仅包含 ATF 或 EIIF 结合位点的 E2A 启动子突变体进行的实验表明，小 t 的反式激活仅涉及 EIIF 转录因子，并且该功能需要共同（残基 1 至 82）和表达为共线蛋白的小 t 独特结构域。相反，大 T 的反式激活至少涉及三种机制。似乎至少有两种涉及 EIIF 转录因子的机制，其中至少一种不需要共同结构域（残基 1 至 82），另一种机制涉及 ATF 因子，并且需要共同结构域和大 T 独特结构域。
Simian virus 40 (SV40) small t and large T antigens can each trans activate the adenovirus (Ad) E2A and the Ad VA-I promoters. The first 82 amino acids of large T and small t are identical. However, this large T-small t common domain between residues 1 and 82 does not trans activate, suggesting that large T and small t each encode separate trans-activation functions. To determine whether the large T or small t unique domains, which are required for trans activation of the E2A promoter, are sufficient for this activity, we have employed expression plasmids separately encoding the common and unique domains of large T and small t. Cotransfection of a large T unique domain expression plasmid efficiently trans activated the E2A promoter. Optimal trans activation by large T required the motif that binds cellular proteins such as the retinoblastoma gene product, which is located in the large T unique domain, and additional large T structures outside this motif. In contrast, the small t unique domain did not trans activate the E2A promoter. Experiments utilizing E2A promoter mutants containing only the ATF- or EIIF-binding sites demonstrated that trans activation by small t involves only the EIIF transcription factor and that this function requires both the common (residues 1 to 82) and the small t unique domains expressed as a colinear protein. trans activation by large T, in contrast, involves at least three mechanisms. There appear to be at least two mechanisms that involve the EIIF transcription factor, at least one of which does not require the common domain (residues 1 to 82) and one mechanism that involves the ATF factor and does require both the common and the large T unique domains.