Recombinant Human PI-9 protein (His-DHFR tag N-Terminus)

Supplementary information

This supplementary information is collated from multiple sources and compiled automatically.

The PI-9 protein also known as serpinB9 is a serine protease inhibitor with a molecular mass of approximately 42 kDa. It is expressed primarily in immune cells such as cytotoxic T lymphocytes and natural killer cells as well as in some neurons and hepatocytes. The protein inhibits proteolytic enzymes to prevent unwanted cell death mainly controlling granzyme B activity.

Biological function summary

PI-9 helps regulate immune cell activity and prevent autoimmunity by inhibiting granule-mediated apoptosis. It functions as part of a complex that manages cell death pathways acting as a guardian against excessive cytotoxic actions by the immune system. Its regulatory role ensures the balance between attacking pathogens and protecting host cells from unnecessary destruction.

Pathways

PI-9 plays an integral role in the apoptotic pathway interacting with proteins like granzyme B to protect host cells from immune-mediated killing. It is also involved in the cellular response to stress especially within the immune system's cytotoxic responses. The protein's interaction with granzyme B highlights its role in maintaining the balance between immune defense and cellular protection.

PI-9 has been linked to autoimmune conditions and cancer. It helps regulate autoimmune responses by preventing excessive apoptosis which could otherwise lead to tissue damage. In cancer PI-9 overexpression is sometimes observed potentially allowing tumor cells to evade immune surveillance. The relationship between PI-9 and granzyme B is important in understanding its dual role in disease contexts.