p53 Tumor Suppressor Protein

p53 tumor suppressor protein (p53) is a labile protein located in the nucleus. Agents which damage DNA induce p53 to become very stable by a post-translational mechanism, allowing its concentration in the nucleus to increase dramatically. The functional structure includes a strong transcriptional activation domain at the amino terminus, a central evolutionary highly conserved sequence-specific DNA binding domain and a tetramerization domain. p53 is a potent transcription factor and once activated it represses transcription of genes containing p53-binding sites (several of which are involved in stimulating cell growth) while stimulating expression of other genes involved in cell cycle control. The wild-type form of p53 exhibits strong anti-oncogenic properties. It arrests the cell cycle in response to DNA damage, thereby allowing DNA repair before the replication of the genome, and induces apoptosis if the damage to the cell is too severe. A loss of p53 function (oncogenic...