Lee C H, Leeds P, Ross J
McArdle Laboratory for Cancer Research, University of Wisconsin, Madison, Wisconsin 53706, USA.
J Biol Chem. 1998 Sep 25;273(39):25261-71. doi: 10.1074/jbc.273.39.25261.
The regulation of mRNA half-lives is determined by multiple factors, including the activity of the messenger RNases (mRNases) responsible for destroying mRNA molecules. Previously, we used cell-free mRNA decay assays to identify a polysome-associated endonuclease that cleaves c-myc mRNA within the coding region. A similar activity has been solubilized and partially purified from a high salt extract of adult rat liver polysomes. Based on a correlation between protein and enzyme activity, the endonuclease is tentatively identified as a approximately 39-kDa protein. It cleaves the coding region stability determinant of c-myc mRNA with considerable specificity. Cleavages occur predominantly in an A-rich segment of the RNA. The endonuclease is resistant to RNase A inhibitors, sensitive to vanadyl ribonucleoside complex, and dependent on magnesium. In these and other respects, the soluble enzyme we have purified resembles the polysome-associated c-myc mRNase.
mRNA半衰期的调节由多种因素决定，包括负责破坏mRNA分子的信使核糖核酸酶（mRNases）的活性。此前，我们利用无细胞mRNA降解分析鉴定出一种多核糖体相关的核酸内切酶，它能在编码区内切割c-myc mRNA。类似的活性已从成年大鼠肝脏多核糖体的高盐提取物中溶解并部分纯化。基于蛋白质与酶活性之间的相关性，该核酸内切酶初步被鉴定为一种约39 kDa的蛋白质。它以相当高的特异性切割c-myc mRNA的编码区稳定性决定因素。切割主要发生在RNA富含A的片段中。该核酸内切酶对核糖核酸酶A抑制剂有抗性，对钒核糖核苷复合物敏感，且依赖镁离子。在这些及其他方面，我们纯化的可溶性酶类似于多核糖体相关的c-myc mRNA酶。
