Shaw P E, Bohmann D, Sergeant A
EMBO J. 1985 Dec 1;4(12):3247-52. doi: 10.1002/j.1460-2075.1985.tb04073.x.
We have examined transcription from the SV40 late promoter in vitro and in vivo. In HeLa whole cell extracts, late transcription is efficient in the absence of T antigen but is impaired by enhancer specific point mutations. In vivo, when replication is prevented, transcription from the late promoter requires T antigen as well as a functional enhancer. However, enhancer sequences fail to potentiate late transcription from replicating templates although, under such conditions, enhancer binding factors do not become limiting. It appears that the SV40 late transcription unit is refractory to enhancer-mediated activation when it is located on a replicating template.
我们已经在体外和体内检测了SV40晚期启动子的转录情况。在HeLa全细胞提取物中，即使没有T抗原，晚期转录也很高效，但会受到增强子特异性点突变的影响。在体内，当复制被阻止时，晚期启动子的转录需要T抗原以及功能性增强子。然而，尽管在这种情况下增强子结合因子不会成为限制因素，但增强子序列无法增强复制模板的晚期转录。似乎当SV40晚期转录单元位于复制模板上时，它对增强子介导的激活具有抗性。
