Eadara J K, Lutter L C
Molecular Biology Research Program, Henry Ford Hospital, Detroit, Michigan 48202, USA.
Virology. 1996 Sep 1;223(1):120-31. doi: 10.1006/viro.1996.0461.
Occupancies of the SPH and GT-IIC sequence motifs in the native SV40 late transcription elongation complex were determined by assessing blockage to restriction enzyme cleavage. Cleavages specific to the transcription elongation complex were quantified by radioactive extension labeling and polymerase run-off analysis. The SPH motif was assayed by Sphl digestion and found to be unoccupied. In contrast, digestion with Pvull at the GT-IIC site was blocked in 36% of the complexes, indicating that approximately a third of the complexes are occupied by factor. This fractional occupancy indicates that there are at least two forms of SV40 late transcription elongation complexes, one form with the GT-IIC site occupied by a factor and another with the site vacant.
通过评估对限制性内切酶切割的阻碍来确定天然SV40晚期转录延伸复合物中SPH和GT-IIC序列基序的占有率。通过放射性延伸标记和聚合酶溢流分析对转录延伸复合物特有的切割进行定量。通过SphI消化检测SPH基序，发现其未被占据。相比之下，在GT-IIC位点用PvuII消化在36%的复合物中受到阻碍，这表明大约三分之一的复合物被因子占据。这种部分占有率表明至少存在两种形式的SV40晚期转录延伸复合物，一种形式中GT-IIC位点被因子占据，另一种形式中该位点为空。
