Sollerbrant K, Akusjärvi G, Linder S, Svensson C
Department of Cell and Molecular Biology, Medical Nobel Institute, Karolinska Institute, Stockholm, Sweden.
Nucleic Acids Res. 1995 Feb 25;23(4):588-94. doi: 10.1093/nar/23.4.588.
Different Gal4 fusion proteins, expressing unrelated transcription activator domains, were found to activate transcription from promoters containing dimerized AP1 DNA binding sites. Transactivation was dependent on the first 74 amino acids of Gal4. A direct interaction between Gal4 and c-Jun was demonstrated using a GSTGal4 fusion protein and in vitro translated human c-Jun. The interaction required the zinc finger containing DNA binding domain of Gal4 and the basic-leucine zipper region of c-Jun. These results demonstrated that the specificity of Gal4 fusion proteins in transient transfection experiments in mammalian cells is not restricted to reporters containing Gal4 binding sites, but also includes promoters containing AP1 binding sites. Furthermore, the Gal4 fusion proteins also activated transcription from a pUC18 vector fragment containing several putative AP1 binding sites. Finally, our results indicate that Gal4 activator proteins binding to Gal4 binding sites and to DNA bound AP1 factors can co-operatively activate transcription.
人们发现，表达不相关转录激活域的不同Gal4融合蛋白能够激活含有二聚化AP1 DNA结合位点的启动子的转录。转录激活依赖于Gal4的前74个氨基酸。使用GSTGal4融合蛋白和体外翻译的人c-Jun证明了Gal4与c-Jun之间存在直接相互作用。这种相互作用需要Gal4含锌指的DNA结合结构域和c-Jun的碱性亮氨酸拉链区域。这些结果表明，Gal4融合蛋白在哺乳动物细胞瞬时转染实验中的特异性不仅限于含有Gal4结合位点的报告基因，还包括含有AP1结合位点的启动子。此外，Gal4融合蛋白还激活了来自含有几个假定AP1结合位点的pUC18载体片段的转录。最后，我们的结果表明，与Gal4结合位点和与DNA结合的AP1因子结合的Gal4激活蛋白可以协同激活转录。
