Polyomavirus Small T Antigens are a group of proteins encoded by the polyomavirus genome. Polyomaviruses are a family of small, non-enveloped DNA viruses that infect humans and animals. The small T antigens are one of the key regulatory proteins of polyomaviruses and play a crucial role in virus replication and transformation.
The small T antigens are characterized by their molecular weight, which typically ranges from 19 to 25 kilodaltons. These proteins are expressed early during the viral life cycle and have multifunctional roles. They interact with several cellular proteins, including tumor suppressors and oncogenes, to manipulate cellular pathways necessary for viral replication.
Functionally, the small T antigens are involved in modulating host cell signaling pathways, particularly those involving cell cycle regulation and apoptosis. They can bind to and inhibit the function of key cellular proteins such as the retinoblastoma protein, p53 tumor suppressor, and protein phosphatase 2A, among others. By interacting with these proteins, the small T antigens promote cell cycle progression and prevent cellular senescence or apoptosis, thereby creating a favorable environment for viral replication.
Moreover, polyomavirus small T antigens exhibit oncogenic properties and can transform certain types of cells in vitro. Their ability to interfere with tumor suppressor pathways and promote cell proliferation has been implicated in the development of certain polyomaviruses-associated cancers, such as Merkel cell carcinoma.
In conclusion, polyomavirus small T antigens are viral proteins that manipulate cellular pathways to facilitate viral replication, inhibit apoptosis, promote cell proliferation, and contribute to oncogenesis.
