P53 gene



The p53 gene is a gene that codes for a protein for tumor suppression. It is
very important for cells in multicellular organisms to suppress uncontrolled
cell division.

Gene

The human p53 gene is located on chromosome 17.

Protein structure

The p53 protein is a phosphoprotein made of ~390 amino acids. It consists of
three units (or domains):

   * A domain that activates transcription factors.
   * A domain that recognizes specific DNA sequences.
   * A domain that recognized damaged DNA, such as misaligned base pairs or
     single-stranded DNA.

p53 protein has been voted molecule of the year.

Mechanism

The p53 protein can regulate the cell in several ways:

   * It can activate DNA repair proteins when it recognizes damaged DNA.
   * It can also hold the cell cycle at the G1/S regulation point on DNA
     damage recognition.
   * It can initiate apoptosis, the programmed cell death, if the DNA damage
     proves to be irrepairable.

Malfunctions

If the p53 gene is damages, tumor suppression is severly reduced. People who
inherit only one functional copy of p53 from their parents will develop
various tumors in early adulthood, a disease known as Li-Fraumeni syndrome.
p53 can also be damaged in cells by mutagens (chemicals, radiation or
viruses), increasing the likelyhood of the cell to divide uncontrolled. More
than 50% of tumors in humans show a mutation or deletion of the p53 gene.

Cancer - List of Famous Cancer Patients - Medical Topics - Medical_Terms - Medicine - Alternative Therapies -