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.

Table of contents

1 Gene 2 Protein structure 3 Mechanism 4 Malfunctions 5 External links

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 damaged, tumor suppression is severely reduced. People who inherit only one functional copy of p53 will most likely develop 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 likelihood that the cell will begin uncontrolled division. More than 50 percent of human tumors contain a mutation or deletion of the p53 gene.

External links

• Structure of p53