Giniger E, Ptashne M
Department of Biochemistry and Molecular Biology, Harvard University, Cambridge, MA 02138.
Proc Natl Acad Sci U S A. 1988 Jan;85(2):382-6. doi: 10.1073/pnas.85.2.382.
The yeast transcriptional regulatory protein GAL4 binds to four sites in the GAL upstream activating sequence and stimulates transcription of the adjacent GAL1 and GAL10 genes. We show here that binding to at least two of these sites is cooperative in vivo. We also measure stimulation of transcription by pairs of GAL4 binding sites and find that the activities of low-affinity binding sites combine synergistically, whereas the activities of high-affinity binding sites combine only additively. We suggest that the synergistic transcriptional stimulatory activity of the naturally occurring GAL4 binding sites is solely a manifestation of cooperative binding of GAL4 protein to DNA and that the activity of a GAL upstream activating sequence is roughly proportional to the number of GAL4 molecules bound.
酵母转录调节蛋白GAL4与GAL上游激活序列中的四个位点结合，并刺激相邻的GAL1和GAL10基因的转录。我们在此表明，在体内与这些位点中的至少两个位点的结合是协同的。我们还测量了成对的GAL4结合位点对转录的刺激作用，发现低亲和力结合位点的活性协同组合，而高亲和力结合位点的活性仅以相加方式组合。我们认为，天然存在的GAL4结合位点的协同转录刺激活性仅仅是GAL4蛋白与DNA协同结合的一种表现，并且GAL上游激活序列的活性大致与结合的GAL4分子数量成正比。
