Walsh K
Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
Mol Cell Biol. 1989 May;9(5):2191-201. doi: 10.1128/mcb.9.5.2191-2201.1989.
A conserved 28-base-pair element in the skeletal actin promoter was sufficient to activate muscle-specific expression when placed upstream of a TATA element. This muscle regulatory element (MRE) is similar in structure to the serum response element (SRE), which is present in the promoters of the c-fos proto-oncogene and the nonmuscle actin genes. The SRE can function as a constitutive promoter element. Though the MRE and SRE differed in their tissue-specific expression properties, both elements bound to the same protein factors in vitro. These proteins are the serum response factor (SRF) and the muscle actin promoter factors 1 and 2 (MAPF1 and MAPF2). The SRF and MAPF proteins were resolved by chromatographic procedures, and they differed in their relative affinities for each element. The factors were further distinguished by their distinct, but overlapping, methylation interference footprint patterns on each element. These data indicate that the differences in tissue-specific expression may be due to a complex interaction of protein factors with these sequences.
当置于TATA元件上游时，骨骼肌肌动蛋白启动子中一个保守的28个碱基对元件足以激活肌肉特异性表达。这个肌肉调节元件（MRE）在结构上与血清反应元件（SRE）相似，后者存在于c-fos原癌基因和非肌肉肌动蛋白基因的启动子中。SRE可作为组成型启动子元件发挥作用。尽管MRE和SRE在组织特异性表达特性上有所不同，但二者在体外均能与相同的蛋白质因子结合。这些蛋白质是血清反应因子（SRF）以及肌肉肌动蛋白启动子因子1和2（MAPF1和MAPF2）。通过色谱法分离出了SRF和MAPF蛋白，它们对每个元件的相对亲和力有所不同。这些因子在每个元件上具有独特但相互重叠的甲基化干扰足迹模式，这进一步区分了它们。这些数据表明，组织特异性表达的差异可能是由于蛋白质因子与这些序列的复杂相互作用所致。
