The PROS1 gene provides instructions for making a protein called protein S that is important for the regulation of blood clotting. Although protein S can work on its own to inhibit certain clotting factors, it often works as a cofactor. Cofactors enhance the function of proteins that speed up chemical reactions (enzymes).
Protein S is made by cells in the liver. The protein circulates in the bloodstream in two forms; it is either attached (bound) to a specific protein, or it occurs by itself in a free form. The free form of protein S can act as a cofactor for an enzyme called activated protein C (APC). APC turns off (inactivates) the blood clotting proteins known as factor Va and factor VIIIa. Protein S also helps a protein called tissue factor pathway inhibitor (TFPI) block the activity of another clotting protein, factor Xa. This inactivation slows down the clotting process so that blood flow is not impaired.
Other Names
PROS; protein S, alpha; PS21; PS22; PS23; PS24; PS25; PSA; THPH5; THPH6; vitamin K-dependent plasma protein S
Related Genetics Topics
Identifiers
- NCBI Gene: 5627
- OMIM: 176880
Source: MedlinePlus Genetics, U.S. National Library of Medicine.
