Protein s

Protein S is a vitamin K-dependent plasma protein that functions as a cofactor to Protein C in the degradation of coagulation factors Factor Va and Factor VIIIa. It is named for Seattle, Washington, where the protein was first identified and isolated.

Function

Protein S is a cofactor to Protein C in the inactivation of Factors Va and VIIIa. It helps to prevent blood clotting. When Protein S is absent, Protein C can not perform its function, leading to an increased risk of developing deep vein thrombosis.

Genetics

The PROS1 gene encodes Protein S in humans. It is located on chromosome 3 (3q11.2). Mutations in this gene can lead to Protein S deficiency, a disorder associated with increased risk of venous thrombosis.

Clinical significance

Protein S deficiency is a disorder associated with increased risk of venous thrombosis. It can be inherited in an autosomal dominant manner, or can be acquired as a result of certain medical conditions, such as liver disease, vitamin K deficiency, and HIV infection.

See also

• Protein C
• Factor V Leiden
• Thrombophilia