Brown C J, Baltz K A, Edenberg H J
Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis 46202-5122.
Gene. 1992 Nov 16;121(2):313-20. doi: 10.1016/0378-1119(92)90136-d.
The sequence 5'-GTGGGTGTGGC (G3T) is important for the efficient initiation of transcription from the human ADH2 promoter. We show here that the purified transcription factor Sp1 binds with high affinity to the G3T site of ADH2 (encoding beta beta-alcohol dehydrogenase), even though the G3T sequence does not contain the canonical Sp1-binding site, GGGCGG. Proteins from mouse liver nuclei and purified Sp1 both footprint the same sequence of the ADH2 promoter with similar patterns. UV crosslinking demonstrates that the major G3T-binding protein in the liver extract is similar in size to Sp1. Mouse liver nuclear extract resembles purified Sp1 in its relative binding affinity to a series of oligodeoxyribonucleotides containing either the Sp1-binding site or variants of the G3T sequence. These data indicate that the G3T sequence can interact with Sp1 and that Sp1 may be important in the expression of ADH2. The G3T sequence from the closely related ADH3 gene (encoding gamma gamma-alcohol dehydrogenase) differs from that of ADH2 in the first two nucleotides; it binds both the liver protein and purified Sp1 with lower affinity. This might explain why ADH3 is expressed at lower levels than ADH2 in the liver.
5'-GTGGGTGTGGC（G3T）序列对于从人ADH2启动子高效起始转录很重要。我们在此表明，纯化的转录因子Sp1与ADH2（编码ββ-醇脱氢酶）的G3T位点具有高亲和力结合，尽管G3T序列不包含典型的Sp1结合位点GGGCGG。来自小鼠肝细胞核的蛋白质和纯化的Sp1对ADH2启动子的相同序列进行足迹分析时具有相似的模式。紫外线交联表明，肝提取物中主要的G3T结合蛋白在大小上与Sp1相似。小鼠肝核提取物在与一系列含有Sp1结合位点或G3T序列变体的寡脱氧核糖核苷酸的相对结合亲和力方面类似于纯化的Sp1。这些数据表明G3T序列可以与Sp1相互作用，并且Sp1可能在ADH2的表达中起重要作用。密切相关的ADH3基因（编码γγ-醇脱氢酶）的G3T序列在前两个核苷酸上与ADH2的不同；它与肝蛋白和纯化的Sp1的结合亲和力较低。这可能解释了为什么ADH3在肝脏中的表达水平低于ADH2。
