Ray R, Miller D M
Department of Internal Medicine, University of Alabama, Birmingham.
Mol Cell Biol. 1991 Apr;11(4):2154-61. doi: 10.1128/mcb.11.4.2154-2161.1991.
A human cDNA clone encoding a c-myc promoter-binding protein was detected by screening a HeLa cell lambda phage expression cDNA library. The library was screened by using an XhoI-NaeI human c-myc P2 promoter fragment as a probe. The recombinant phage encoded a fusion protein, myc-binding protein 1 (MBP-1), which had an apparent molecular size of 40 kDa. A corresponding protein with a molecular size of 35 kDa was present in a HeLa cell extract. Sequence analysis of the cloned gene reveals an open reading frame of 1,038 bp with a 3' untranslated region of 378 bp. The predicted protein sequence contains a proline-rich region in the amino terminus but does not demonstrate a known DNA-binding domain. DNase I footprint analysis demonstrates that MBP-1 binds to the sequence just 5' of the TATA box sequence of the human c-myc P2 promoter. MBP-1 cDNA hybridizes to a 1.4-kb mRNA from HeLa and HL-60 cells, indicating that the cDNA insert (1,416 bp) is a full-length clone. Coexpression of the MBP-1 protein repress transcription from the human c-myc promoter, suggesting that MBP-1 may act as a negative regulatory factor for the human c-myc gene.
通过筛选HeLa细胞λ噬菌体表达cDNA文库，检测到一个编码c-myc启动子结合蛋白的人cDNA克隆。使用XhoI-NaeI人c-myc P2启动子片段作为探针筛选该文库。重组噬菌体编码一种融合蛋白，即myc结合蛋白1（MBP-1），其表观分子大小为40 kDa。HeLa细胞提取物中存在一种分子大小为35 kDa的相应蛋白。对克隆基因的序列分析揭示了一个1038 bp的开放阅读框以及一个378 bp的3'非翻译区。预测的蛋白质序列在氨基末端含有一个富含脯氨酸的区域，但未显示出已知的DNA结合结构域。DNase I足迹分析表明，MBP-1与人c-myc P2启动子TATA盒序列上游的序列结合。MBP-1 cDNA与HeLa和HL-60细胞的1.4 kb mRNA杂交，表明cDNA插入片段（1416 bp）是一个全长克隆。MBP-1蛋白的共表达抑制人c-myc启动子的转录，提示MBP-1可能作为人c-myc基因的负调控因子发挥作用。
