Sakurai H, Hiraoka Y, Fukasawa T
Laboratory of Molecular Genetics, Keio University School of Medicine, Tokyo, Japan.
Proc Natl Acad Sci U S A. 1993 Sep 15;90(18):8382-6. doi: 10.1073/pnas.90.18.8382.
The yeast auxiliary transcription factor GAL11, a candidate for the coactivator, was partially purified from yeast cells, and its function was characterized in a cell-free transcription system. The partially purified GAL11 protein stimulated basal transcription from the CYC1 core promoter by a factor of 4-5 at the step of preinitiation complex formation. GAL11 protein also enhanced transcription activated by general regulatory factor 1, GAL4-AH, or GAL4-VP16 to the same extent as the basal transcription. Therefore, the apparent potentiation of the activators by GAL11 was attributable to the stimulation of basal transcription. The wild-type GAL11 protein (but not a mutant-type protein) produced in bacteria stimulated transcription as effectively as GAL11 from yeast. These results suggest that GAL11 functions as a positive cofactor of basal and activator-induced transcription in a cell-free transcription system.
酵母辅助转录因子GAL11是共激活因子的候选者，它从酵母细胞中得到部分纯化，并在无细胞转录系统中对其功能进行了表征。部分纯化的GAL11蛋白在起始前复合物形成步骤中，将CYC1核心启动子的基础转录提高了4至5倍。GAL11蛋白还将由通用调节因子1、GAL4-AH或GAL4-VP16激活的转录增强到与基础转录相同的程度。因此，GAL11对激活因子的明显增强作用归因于对基础转录的刺激。在细菌中产生的野生型GAL11蛋白（而非突变型蛋白）与酵母中的GAL11一样有效地刺激转录。这些结果表明，在无细胞转录系统中，GAL11作为基础转录和激活因子诱导转录的正辅助因子发挥作用。
