p53 Protein, human

p53, also known as tumor protein 53 (TP53), is a transcription factor that regulates the cell cycle and hence functions as a tumor suppressor. It is very important for cells in multicellular organisms to suppress cancer. p53 has been described as 'the guardian of the genome' or the 'master watchman', referring to its role in conserving stability by preventing genome mutation. Human p53 is 393 amino acids long and has three domains: (1)An N-terminal transcription-activation domain (TAD), which activates transcription factors;(2) A central DNA-binding core domain (DBD), which contains zinc molecules and Arginine Amino Acid Residues; (3) A C-terminal homo-oligomerisation domain (OD). p53 has many anti-cancer mechanisms: (1)It can activate DNA repair proteins when DNA has sustained damage; (2)It can also hold the cell cycle at the G1/S regulation point on DNA damage recognition; (3) It can initiate apoptosis, the programmed cell death, if the DNA damage proves to be irreparable.