Graves B J, Johnson P F, McKnight S L
Cell. 1986 Feb 28;44(4):565-76. doi: 10.1016/0092-8674(86)90266-7.
We have partially purified, from rat liver, a nuclear protein fraction with sequence-specific affinity to a promoter domain shared by the herpesvirus tk gene and the Moloney murine sarcoma virus LTR. For both promoters, the protein-binding domain occurs roughly 80 bp upstream of the mRNA cap site and harbors the pentanucleotide sequence 5'-CCAAT-3'. The MSV LTR pentanucleotide occurs on the coding strand in an orientation pointing toward the retroviral transcription unit. The HSV tk pentanucleotide occurs on the noncoding strand in an orientation pointing away from the gene. Assays in microinjected frog oocytes and transfected mouse L cells indicate that equivalent point mutations, introduced at each residue of the CAT pentanucleotide of each promoter, lead to similar changes in promoter activity. Furthermore, they similarly alter binding of the nuclear protein fraction. Surprisingly, a C to G transversion at the first residue of the CAT pentanucleotide, which severely impairs the activity of both promoters, appears to increase affinity of the CAT binding protein.
我们已从大鼠肝脏中部分纯化出一种核蛋白组分，它对疱疹病毒tk基因和莫洛尼氏鼠肉瘤病毒LTR共有的启动子结构域具有序列特异性亲和力。对于这两种启动子，蛋白质结合结构域大约位于mRNA帽位点上游80 bp处，并含有五核苷酸序列5'-CCAAT-3'。MSV LTR五核苷酸位于编码链上，其方向指向逆转录病毒转录单元。HSV tk五核苷酸位于非编码链上，其方向背离该基因。在显微注射的蛙卵母细胞和转染的小鼠L细胞中进行的测定表明，在每个启动子的CAT五核苷酸的每个残基处引入的等效点突变，会导致启动子活性发生类似变化。此外，它们同样会改变核蛋白组分的结合。令人惊讶的是，CAT五核苷酸第一个残基处的C到G颠换严重损害了两种启动子的活性，但似乎增加了CAT结合蛋白的亲和力。
