P53: Difference between revisions

p53 tumor suppressor is a flexible molecule composed of four identical protein chains. Flexible molecules are difficult to study by x-ray crystallography because they do not form orderly crystals, and if they do crystallize, the experimental images are often blurry.<applet load='1olg' size='400' frame='true' align='right' /> So, p53 has been studied in parts, by removing the flexible regions and solving structures of the pieces that form stable structures. Three of these compact, globular portions, termed "domains", have been studied. At the center of p53 is a tetramerization domain (PDB entry [[1olg]] ) that ties the four <scene name='P53/1olg/1'>view it</scene> chains together. A long flexible region in each chain then connects to the second stable domain: a large DNA-binding domain (PDB entry [[1tup]] <scene name='P53/1tup/1'>view it</scene>) that is rich in arginine residues that interact with DNA. This domain recognizes specific regulatory sites on the DNA. The third stable domain studied thus far is the transactivation domain (PDB entry [[1ycq]] <scene name='P53/1ycq/1'>view it</scene>), found near the end of each arm, that activates the DNA-reading machinery.