Hehlgans T, Strominger J L
Department of Biochemistry and Molecular Biology, Harvard University, Cambridge, MA 02138, USA.
J Immunol. 1995 May 15;154(10):5181-7.
A previously unrecognized element, located downstream of the start site of transcription in the first exon of the DR alpha gene, has been defined that enhances promoter activity up to eightfold in a position-dependent manner. Mutations in this DNA-binding site abolished binding of a nuclear factor in human B cell nuclear extract and decreased the activity of the DR alpha promoter to a basal level. Significant sequence homology of this element was found in the DNA of the DR beta, DP alpha and -beta, and DQ alpha genes, always located downstream of the transcriptional start site. The nuclear factor binds to the DR alpha and DP alpha element but not to the element in the DQ alpha gene. It was identified as NF-E1 (YY1). This protein, previously identified by its binding to the Ig kappa 3' enhancer and the Ig heavy chain mu E1 site, thus also appears to be quite important in the regulation of MHC class II gene expression.
在DRα基因第一个外显子转录起始位点下游发现了一个以前未被识别的元件，该元件可将启动子活性以位置依赖的方式增强至八倍。该DNA结合位点的突变消除了人B细胞核提取物中一种核因子的结合，并将DRα启动子的活性降低至基础水平。在DRβ、DPα和-β以及DQα基因的DNA中发现了该元件的显著序列同源性，且该元件总是位于转录起始位点的下游。该核因子与DRα和DPα元件结合，但不与DQα基因中的元件结合。它被鉴定为NF-E1（YY1）。这种蛋白质以前通过与Igκ3'增强子和Ig重链μE1位点结合而被鉴定，因此在MHC II类基因表达的调控中似乎也相当重要。
