Technical Data
Protein S (HRP)
Protein S (PS) is a vitamin K-dependent glycoprotein produced in the liver, endothelium and megakaryocytes. The concentration of PS in plasma is ~25ug/ml (~325nM) where it acts as a cofactor in the anticoagulant activity of activated Protein C. A deficiency of Protein S (quantitative or qualitative) is a risk factor for vascular thrombosis. Protein S is expressed as a single chain molecule with a molecular weight of 77kD. The structure of PS is similar to many other vitamin-K dependent coagulation proteins, consisting of an N-terminal calcium binding domain of 10 gamma-carboxyglutamic acid (gla) residues, followed by a thrombin-sensitive loop region and 4 EGF-like domains. The C-terminal domain does not contain the usual catalytic triad of a proenzyme, but seems instead to be involved in the binding of PS to C4b-binding protein (C4bp). Protein S binds to activated Protein C (APC) in the presence of calcium and negatively charged phospholipid surface to allow APC to proteolytically inactivate coagulation cofactors Va and VIIIa. Enzymatic regulation of PS cofactor activity is through cleavage of PS in the thrombin-sensitive loop region by thrombin or other enzymes, resulting in the loss of calcium binding properties and APC cofactor activity. Another regulatory mechanism is to reduce the availability of PS by the binding of PS to C4bp. In plasma, approximately 60% of Protein S circulates in non-covalent complex with C4bp, making it unavailable for APC cofactor activity. The binding of PS to C4bp may be important in localizing C4bp to damaged cell membranes where it may control activation of complement by the classical pathway (1-3).

Suitable for use in ELISA and Immunoelectrophoresis. Other applications not tested.

Recommended Dilution:
Optimal dilutions to be determined by the researcher.

Storage and Stability:
May be stored at 4C for short-term only. For long-term storage, store at -20C. Aliquots are stable for at least 12 months at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer. Labeled with horseradish peroxidase (HRP). Sodium azide is a potent inhibitor of peroxidase and should not be added to HRP conjugates. HRP conjugates are sensitive to light.
200ug4C (-20C Glycerol)Blue IceHumanSheep
Human Protein S (PS) isolated from plasma.
Supplied in a buffered stabilizer solution with 50% glycerol. Labeled with Horseradish Peroxidase (HRP).
Recognizes human Protein S at ~77kD.
Intended for research use only. Not for use in human, therapeutic, or diagnostic applications.
1. Broze, G.J. & Miletech, J.P., Biochemistry and Physiology of Protein C, Protein S and Thrombomodulin: in Hemostasis and Thrombosis, 3rd Edtion, eds. R.W. Colman, J. Hirsh, V.J. Marder and E.W. Salzman, pp259-276, J.B. Lippincott Co., Philadelphia PA, USA (1994). 2. Comp, P.C., et al., Blood 67: 504-508 (1986). 3. Schwaalbe, R.A., Dahlback, B., Nelsestuen, G.L., JBC 265: 21,749-21,757 (1990).