HEK293和HeLa细胞分别被Np95/ICBP90-likeRINGfingerprotein(NIRF)和P53转染后,细胞上清和免疫沉淀产物用SDS-聚丙烯酰胺凝胶电泳免疫印迹法分析;细菌合成GST-P53后,用GSTpull-down技术检测NIRF与P53相互作用;在GST-P53、E1、E2和NIRF体外泛素化反应系统中,检测NIRF对P53的体外泛素化.结果表明:NIRF能与P53相互作用,NIRF不仅能与P53特异性结合,而且还会将P53泛素化,这种相互作用在细胞内和细胞外均能发生.推测NIRF可能是P53的一个新的负调节蛋白. After HEK293 and HeLa cells were transfected with Np95 / ICBP90-likeRINGfingerprotein (NIRF) and P53 respectively, the cell supernatant and immunoprecipitation products were analyzed by SDS-polyacrylamide gel electrophoresis and immunoblotting. After GST-P53 was synthesized by GSTpull- down technique was used to detect the interaction between NIRF and P53.The in vitro ubiquitination of P53 by NIRF was detected in the in vitro ubiquitination system of GST-P53, E1, E2 and NIRF.The results showed that NIRF could interact with P53, It binds specifically to P53 and ubiquitinates P53, and this interaction occurs both intracellularly and extracellularly.It is hypothesized that NIRF may be a new negative regulatory protein of P53.