Sáfrány G, Perry R P
Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, PA 19111.
Proc Natl Acad Sci U S A. 1993 Jun 15;90(12):5559-63. doi: 10.1073/pnas.90.12.5559.
The mouse gene that encodes the delta transcription factor has been cloned and characterized. This gene spans 23 kb and is composed of five exons and four introns. The first exon consists of a long (431 bp), (C+G)-rich, untranslated segment and a 679-bp coding segment, which specifies the unusual tracts of consecutive acidic residues and histidines and the long alanine-glycine stretches. The sequence that encodes the four zinc-finger motifs of this protein is interrupted by two introns. Nuclease protection experiments revealed a major transcriptional start point and several additional start points distributed over a 28-bp segment. Transfection experiments with 5' and 3' deletion mutants localized the promoter to a (C+G)-rich region that is < 700 bp upstream and no more than 32 bp downstream of the major start point. An especially critical promoter element lies between -58 and -18 and contains a high-affinity Sp1 binding site, as demonstrated by electrophoretic mobility-shift experiments with nuclear extract and recombinant Sp1 proteins. Several striking similarities between the delta gene and genes encoding other transcription factors and regulatory proteins are noted and discussed with respect to their possible biological significance.
编码δ转录因子的小鼠基因已被克隆并进行了特性分析。该基因跨度为23kb，由5个外显子和4个内含子组成。第一个外显子由一个长的（431bp）、富含（C+G）的非翻译区段和一个679bp的编码区段组成，该编码区段指定了连续酸性残基和组氨酸的异常区域以及长的丙氨酸-甘氨酸延伸段。编码该蛋白质四个锌指基序的序列被两个内含子打断。核酸酶保护实验揭示了一个主要转录起始点和分布在一个28bp区段上的几个额外起始点。用5'和3'缺失突变体进行的转染实验将启动子定位到一个富含（C+G）的区域，该区域位于主要起始点上游<700bp且下游不超过32bp处。一个特别关键的启动子元件位于-58至-18之间，并且含有一个高亲和力的Sp1结合位点，这通过用核提取物和重组Sp1蛋白进行的电泳迁移率变动实验得以证明。δ基因与编码其他转录因子和调节蛋白的基因之间存在几个显著的相似之处，并就其可能的生物学意义进行了讨论。
