摘要
业已证明，鸡ｎＡｃｈＲγ亚基基因５＇连接区，－５０９／－３０２，－３２４／＋３６片段可独立激活异源启动子ＳＶ４０的转录活性；γ基因近端两个Ｅ盒子（ＣＡＮＮＴＧ）与生肌调节因子（ｍｙｏｇｅｎｉｎ）的相互作用及转录激活分析表明，近端两个Ｅ盒于是γ启动子活性必不可少的，但却是不充分的。利用胶阻滞和ＤＮａｓｅⅠ足纹试验观察了鸡ｎＡｃｂＲγ基因远端Ｅ盒子与ＧＳＴ－ｍｙｏｇｅｎｉｎ融合蛋白的相互作用。胶阻滞试验证明，－５３８／－２８８片段可与ｍｙｏｇｅｎｉｎ相互结合，引起（３２）￣ｐ标记的ＤＮＡ片段在ＰＡＧＥ中迁移率减慢，这种胶阻滞现象可被含Ｅ盒子的未标记片段消除，并被抗鸡ｍｙｏｇｅｎｉｎ单克隆抗体或抗血清所改变。ＤＮａｓｅⅠ足纹试验证明，ｍｙｏｇｅｎｉｎ系通过γ基因转录起始点上游－４２９／－４２４及－４６３／－４５８两个Ｅ盒子与γ基因５＇连接区－５３８／－２８８相互作用。
The functional and structural analysis of the linker region between the chick AChR & and γ-subunit genes showed it to be responsible for the specific expression of the γsubunit gene. Binding and activation functions of a 360-bp sequence (-324 to +306) which contains proximal E boxes (E1 and E2) in the γ-subunit promoter were previously reported (Cell. Mol. Neurobiol. 1992, 12: 241-258). Using gel shift assay, the binding of myogenic bHLH factor myogenin to the -538/-288 fragment of the chick AChR γ-subunit gene has been performed. The shifted bands could be abolished by the unlabelled -538/-288 fragment, but not by -275/-50 fragment without E box, and the shifted bands could also be changed by anti-myogenin serum or anti-myogenin monoclonal antibody. The DNaseⅠfootprinting indicated that myogenin binded to the two distal E boxes located at -429/-424 and -436/-458 relative to transcription start site of the gene.
基金
国家自然科学基金
