p53 gene

• codes for p53 protein
• normal p53 protein functions at crucial cell-cycle checkpoints 9mainly G1) to stop cell cycle when damaged DNA is deteced
• Normal p53 protein is an activator which initiates transcription of

  1. p21 gene -> p21 protein binds to cyclin-dependent kinases protein -> halts cell cycle -> allows time for cell to repair DNA
  2. DNA repair genes -> protein repairs damaged DNA
  3. "suicide genes" -> protein products cause cell death via apoptosis -> DNA damage is irreparable
• p53 protein -> directly involved in DNA repair by interacting with DNA polymerase in base excision repair
• Cell cycle inhibiting pathway:

  1. DNA damage acts as signal that is passed via
  2. protein kinases
  3. leads to activation of p53 protein -> promotes transcription of gene -> codes for a protein -> suppression of cell division ensures that damaged DNA is not replicated -> DNA damage is irreparable -> p53 leads to apoptosis