T antigen

T antigen or Tumor antigen is a protein complex that is expressed in cells infected with certain types of viruses, such as the Simian Virus 40 (SV40). The T antigen plays a crucial role in the viral life cycle and is also implicated in the transformation of normal cells into cancerous cells.

Function

The primary function of the T antigen is to initiate the replication of the viral genome in the host cell. It does this by binding to the origin of replication on the viral DNA and recruiting the host's DNA replication machinery. This allows the virus to replicate its genome and produce new virus particles.

In addition to its role in viral replication, the T antigen also has the ability to transform normal cells into cancerous cells. This is achieved by the T antigen's ability to bind and inactivate two key tumor suppressor proteins, p53 and Rb. By inactivating these proteins, the T antigen disrupts the normal cell cycle control mechanisms, leading to uncontrolled cell growth and the potential development of cancer.

Clinical significance

Due to its role in cell transformation, the T antigen is of significant interest in cancer research. It has been found to be expressed in a variety of human cancers, including mesothelioma, brain tumors, and osteosarcoma. The presence of T antigen in these cancers suggests a possible role for SV40 or similar viruses in their development.

Furthermore, the T antigen is also being investigated as a potential target for cancer therapy. Strategies include the development of drugs that can inhibit the function of the T antigen, thereby preventing it from inactivating tumor suppressor proteins and disrupting cell cycle control.

See also

• Oncovirus
• Cancer
• Virology

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