Dynan W S, Tjian R
Cell. 1983 Mar;32(3):669-80. doi: 10.1016/0092-8674(83)90053-3.
A new fractionation procedure separates a whole-cell HeLa extract into three components required for accurate in vitro transcription. One component (Sp1) is a promoter-specific factor required for transcription of the SV40 early and late promoters, but not for transcription of other promoters we have tested. The second component (Sp2) is a general factor required for transcription of the SV40 promoters and a series of others, including the adeno-virus 2 major late promoter, the human beta-globin promoter and the avian sarcoma virus promoter. The third component is a fraction containing the endogenous RNA polymerase II. When SV40 and adenovirus templates were present simultaneously in an in vitro transcription reaction, addition of the Sp1 factor stimulated SV40 early promoter transcription 40-fold, and inhibited adenovirus major late promoter transcription by 40%. This finding suggests that Sp1 is involved in promoter selection, and is not merely a general transcription stimulatory factor.
一种新的分级分离程序可将全细胞HeLa提取物分离成准确进行体外转录所需的三种成分。一种成分（Sp1）是一种启动子特异性因子，是SV40早期和晚期启动子转录所必需的，但不是我们测试过的其他启动子转录所必需的。第二种成分（Sp2）是一种通用因子，是SV40启动子以及一系列其他启动子转录所必需的，包括腺病毒2主要晚期启动子、人β-珠蛋白启动子和禽肉瘤病毒启动子。第三种成分是含有内源性RNA聚合酶II的级分。当SV40和腺病毒模板同时存在于体外转录反应中时，添加Sp1因子可使SV40早期启动子转录增强40倍，并使腺病毒主要晚期启动子转录抑制40%。这一发现表明，Sp1参与启动子选择，而不仅仅是一种通用的转录刺激因子。
