Tumor protein p53, also known as
p53,
cellular tumor antigen p53 (
UniProt name),
phosphoprotein p53,
tumor suppressor p53,
antigen NY-CO-13, or
transformation-related protein 53 (TRP53), is any
isoform of a protein encoded by homologous
genes in various organisms, such as
TP53 (humans) and
Trp53 (mice). This homolog (originally thought to be, and often spoken of as, a single protein) is crucial in
multicellular organisms, where it prevents
cancer formation, thus, functions as a
tumor suppressor. As such, p53 has been described as "the guardian of the
genome" because of its role in conserving stability by preventing genome mutation. Hence
TP53 is classified as a
tumor suppressor gene. The name
p53 was given in 1979 describing the apparent
molecular mass;
SDS-PAGE analysis indicates that it is a 53-
kilodalton (kDa) protein. However, the actual mass of the full length p53 protein (p53a) based on the sum of masses of the
amino acid residues is only 43.7 kDa. This difference is due to the high number of
proline residues in the protein, which slow its migration on SDS-PAGE, thus making it appear heavier than it actually is. In addition to the full length protein, the human
TP53 gene encodes at least 15 protein isoforms, ranging in size from 3.5 to 43.7 kDa. All these p53 proteins are called the
p53 isoforms. The
International Cancer Genome Consortium has established that the TP53 gene is the most frequently mutated gene (>50%) in human cancer, indicating that the
TP53 gene plays a crucial role in preventing cancer formation.
TP53 gene encodes proteins that bind to DNA and regulate gene expression to prevent mutations of the genome.