ADP-RIBOSYLATION CYCLES

单-ADP-核糖化是蛋白质的可逆修饰，NAD：精氨酸-ADP-核糖基转移酶和ADP-核糖精氨酸水解酶催化ADP-核糖化循环的相反臂。先前的研究已经检测了小鼠ADP-核糖精氨酸水解酶基因的结构。5侧翼启动子区域在-199到-89之间有一个关键的调控元件。该区域被发现在许多细胞系中起作用，这表明需要一个相对常见的转录因子。进一步的启动子突变分析和电泳迁移率改变分析证实了一个阳性的GC-box元件(-107--95)；利用超转移分析发现Sp1和Sp3与该基序结合。在缺乏内源性Sp1的果蝇SL2细胞的共转移实验中，Sp1被发现以一种依赖于完整Sp1结合基序的方式反式激活ADP-核糖精氨酸水解酶启动子。Sp1转录因子的启动子活性模式和参与程度与先前发现的在哺乳动物组织中广泛表达的水解酶是一致的。-ADP-核糖基化、ADP-核糖精氨酸水解酶

Mono-ADP-ribosylation is a reversible modification of proteins, with NAD: arginine ADP-ribosyltransferases and ADP-ribosylarginine hydrolases catalyzing opposing arms of an ADP-ribosylation cycle. Prior studies have examined the structure of the mouse ADP-ribosylarginine hydrolase gene. The 5 flanking promoter region was shown to have a critical regulatory element at -199 to -89. This region was found to function in a number of cell lines, suggesting the requirement for a relatively common transcription factor. Further mutational analysis of the promoter and electrophoretic mobility shift assays identified a positive GC-box element (-107- -95); using supershift assays, Sp1 and Sp3 were found to bind to this motif. In cotransferction experiments using Drosophila SL2 cells, which lack endogenous Sp1, Sp1 was found to transactivate the ADP-ribosylarginine hydrolase promoter in a manner dependent on the presence of an intact Sp1-binding motif. The promoter activity pattern and involvement of Sp1 transcription factors are consistent with prior observations showing widespread hydrolase expression in mammalian tissues. - ADP-ribosylation, ADP- ribosylarginine hydrolase