Sorger P K, Pelham H R
EMBO J. 1987 Apr;6(4):993-8. doi: 10.1002/j.1460-2075.1987.tb04850.x.
The isolation and complete DNA sequence of a rat genomic clone encoding hsc73, the major hsp70-like protein found in growing cells is described. Unlike the heat-inducible genes characterized so far, the hsc73 gene is interrupted by introns, and there are also numerous intronless hsc73 pseudogenes in the rat genome. We show that the levels of hsc73 mRNA are approximately 5-fold higher in rapidly growing tissue-culture cells than in cells whose growth has been arrested by serum starvation. The abundance of hsc73 mRNA is not significantly increased by heat shock of either fed or starved cells. The hsc73 promoter contains putative binding sites for transcription factor Sp1, two CCAAT boxes and, surprisingly, two matches to the consensus heat-shock regulatory element. When fused to the CAT gene and transfected into COS or HeLa cells, the promoter is constitutively active, showing only a small induction by heat shock. Deletion of some constitutive elements makes it more strongly heat-inducible. The gene thus appears to be subject to more than one form of regulation, mediated by different promoter elements that are intermingled.
本文描述了一个编码hsc73的大鼠基因组克隆的分离及完整DNA序列，hsc73是在生长细胞中发现的主要的类hsp70蛋白。与迄今已鉴定的热诱导基因不同，hsc73基因被内含子打断，并且在大鼠基因组中也存在许多无内含子的hsc73假基因。我们发现，在快速生长的组织培养细胞中，hsc73 mRNA的水平比因血清饥饿而生长停滞的细胞中大约高5倍。无论是喂食的细胞还是饥饿的细胞，热休克都不会显著增加hsc73 mRNA的丰度。hsc73启动子包含转录因子Sp1的假定结合位点、两个CCAAT框，令人惊讶的是，还有两个与共有热休克调节元件匹配的序列。当与CAT基因融合并转染到COS或HeLa细胞中时，该启动子具有组成型活性，热休克仅使其有少量诱导。删除一些组成型元件会使其更强烈地热诱导。因此，该基因似乎受到不止一种形式的调控，由相互交织的不同启动子元件介导。
