期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1981
卷号：78
期号：5
页码：2932-2936
DOI：10.1073/pnas.78.5.2932
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Malignant cells of the mouse transformed by a variety of different agents have been found to express high levels of a 53,000 Mr phosphoprotein (designated p53). Little or no p53 can be detected in normal mouse cells. The nucleus appears to be the predominant site of p53 localization in transformed cells. p53-related antigens are also found in transformed cells of rat, hamster, rabbit, and human. In cells transformed by simian virus 40 (SV40), p53 forms a complex with SV40 tumor (t) antigen, resulting in the coprecipitation of T antigen by monoclonal p53 antibodies. Immune complexes of p53 precipitated from extracts of SV40- or methylcholanthrene-transformed cells by monoclonal p53 antibodies have protein kinase activity. This enzymatic activity is dependent upon divalent cations, utilizing Mn2+ more effectively than Mg2+. The phosphorylation of p53 in this kinase reaction has been found to involve serine and threonine, but not tyrosine residues. In view of the finding that the transforming proteins of several different oncogenic viruses have kinase activity, the association of this activity with p53 is important with regard to the possibility of a common pathway of transformation by diverse agents.
