Protein S

Patent Granted Protein S is a vitamin K-dependent plasma glycoprotein synthesized in the endothelium. In the circulation, Protein S exists in two forms: a free form and a complex form bound to complement protein C4b-binding protein (C4BP). In humans, protein S is encoded by the PROS1 gene.[1][2] In 1979, researchers in Seattle, Washington first discovered protein S and arbitrarily named it after the city of its discovery.