Regulation of p53
One of the most important molecules that regulate p53 is Mdm2 (purple), the product of an oncogene. When bound to p53, Mdm2 prevents p53 from properly binding to DNA to activate other genes. This inactive form of p53 is normally present in cellular reserve. Besides preventing p53 from binding to DNA, Mdm2 can also tag p53 for degradation by the proteasome, the component of the cell that removes unneeded proteins.
A central yellow blob with four gray tails extending from it. About midway along each tail is a large green blob. At the end of each tail is a small red blob. Each red blob has a larger purple blob attached to it. Each pair of red and purple blobs is circled in purple and labeled M-d-m-2.