Jamal S, Ziff E B
Howard Hughes Medical Institute, Department of Biochemistry, New York University Medical Center, N.Y. 10016, USA.
Oncogene. 1995 Jun 1;10(11):2095-101.
Using recombinant baculovirus expressed p53 and Raf proteins, we show that activated Raf-1 kinase can phosphorylate mouse p53 in vitro. We also show that co-expression of vRaf and p53 in NIH3T3 fibroblasts, potentiates the ability of p53 to transactivate a minimal promoter with a p53 cognate DNA binding site. A dominant negative mutant of Raf inhibits the transactivation function of p53 in NIH3T3 fibroblasts. Incubation of Raf-1 kinase with a series of p53 derived synthetic peptides maps the Raf-1 phosphorylation sites to the 27 amino terminal residue region of p53 which coincides with the transactivation domain. Phosphorylation occurs on serines which are phosphorylated in vivo. Our results suggest that the transactivation function of p53 can be regulated by a signaling cascade involving Raf.
利用重组杆状病毒表达的p53和Raf蛋白，我们发现活化的Raf-1激酶在体外可使小鼠p53磷酸化。我们还发现，在NIH3T3成纤维细胞中共表达vRaf和p53，可增强p53反式激活具有p53同源DNA结合位点的最小启动子的能力。Raf的显性负性突变体可抑制NIH3T3成纤维细胞中p53的反式激活功能。用一系列p53衍生的合成肽与Raf-1激酶一起温育，可将Raf-1磷酸化位点定位到p53的27个氨基末端残基区域，该区域与反式激活结构域重合。磷酸化发生在体内被磷酸化的丝氨酸上。我们的结果表明，p53的反式激活功能可由涉及Raf的信号级联调节。
