Complex of Simian Virus Large T Antigen and p53 Can Bind DNA Specifically

• Main Authors: Shih-Bin Long, 龍世斌
• Other Authors: Ming-Derg Lai
• Format: Others
• Language: zh-TW
• Published: 1993
• Online Access: http://ndltd.ncl.edu.tw/handle/60297996605105235026

碩士 === 國立成功大學 === 生物化學研究所 === 81 === Human p53, a 53 Kd protein, is composed of 393 amino acids. As a transcriptional factor, it plays a major role in cellular growth , differentiation and DNA repair. It has been found that p53 protein can form complex with a number of viral transforming antigens, such as large T antigen of SV40, E1B antigen of adenovirus. It is thought that the inhibition of normal p53 function may be an essential step in cellular trnsformation.It was previously established that formation of the complex of viral transforming antigen with p53 could interfere with its DNA binding ability and thus its transcriptional activity. In this way, p53 protein was rendered functionless. Despite this, we discovered that the p53-large T complex still retained DNA binding ability in COS-1, a large T transformed African monkey cell line, and in 1A3, a temperature- sensitive SV40-transformed murine pituitary cell line. By using gel retardation assay, we found that the p53 could bind specifically to RGC and consensus probe. Addition of anti-p53 and large T antibodies can produce supershifting of the bands. In addition, the combined gel retardation immunoblot experiment showed that the large T antigen and p53 exited in the same band. Our results suggest that the large T antigen-p53 complex can bind to DNA. It can be deduced that large T antigen interfere with p53 functioning either by directly inhibiting binding of p53 to its cognate site or by indirectly repressing the transcriptional activity of DNA- bound p53.