Biochemical properties of the growth suppressor/oncoprotein p53.

The cellular p53 protein is so called because of its molecular weight as determined by SDS-polyacrylamide gel electrophoresis. It was originally classified as a nuclear oncogene product when it was shown by DNA transfection experiments that p53 is able to extend the lifespan of primary rodent cell cultures and to cooperate with an activated ras oncogene to achieve complete transformation of primary cells. However, there is now conclusive evidence that loss of normal p53 expression may be an important step in cell transformation and tumorigenesis. Furthermore, it has been shown that mutant p53 was used for the experiments demonstrating the immortalizing and transforming capacity of p53. Wild-type p53 seems to negatively regulate cell growth and division. So far, the basic function of p53 is not known. Biochemical variability seems to be a key feature of p53 and an understanding of biochemical variations in the p53 protein may contribute to an understanding of how p53 is regulated or how p53 may regulate cell proliferation. Thus, the present review will focus on the biochemical properties of p53.