Protein S Paired Antibody Set
Affinity’s Protein S Paired Antibody Set consists of matched capture and detecting antibodies that have been titrated and optimized for use in sandwich style ELISA assays. The product as provided contains sufficient capture and detecting antibodies for five full 96-well microplates and contains a detailed protocol sheet containing directions for use, recipes for solutions and sources for additional materials required. This Protein S Paired Antibody Set is intended to facilitate the end user in establishing an “in-house” immunoassay for research purposes only and must not be used for diagnostic applications. Assay validation is the responsibility of the end user.
Product Code: PS-EIA
- Capture Antibody (PS-EIA-C): One yellow-capped vial containing 0.5 ml of polyclonal affinity purified anti-Protien S antibody for coating plates.
- Detecting Antibody (PS-EIA-D): One red-capped tube containing 0.5 ml of peroxidase conjugated affinity-purified polyclonal anti-Protein S antibody for detection of captured Protein S.
Species Cross Reactivity: View Chart
Product Datasheet: Protein S Matched Pair Antibody Set for ELISA
Description of Protein S (PS)
Protein S (PS) is a vitamin K-dependent glycoprotein produced in the liver, endothelium and megakaryocytes. The concentration of PS in plasma is ~25 μg/ml (~325 nM) 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 77 kDa. The structure of PS is similar to many other vitamin-K dependent coagulation proteins, consisting of an N-terminal calcium binding domain of 10 γ-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 pathway1-3.
References and Reviews:
- Broze GJ, Miletich JP; Biochemistry and Physiology of Protein C, Protein S and Thrombomodulin; in Hemostasis and Thrombosis, 3rd Edition, eds. RW Colman, J Hirsh, VJ Marder and EW Salzman, pp 259-276, J.B. Lippincott Co., Philadelphia PA, USA, 1994.
- Comp PC, Doray D, Patton D, Esmon CT; An Abnormal Plasma Distribution of Protein S Occurs in Functional Protein S Deficiency. Blood 67, pp 504-508, 1986.
- Schwalbe RA, Dahlback B, Nelsestuen GL; Independent Association of Serum Amyloid P Component, Protein S and Complement C4b with C4b-binding Protein and Subsequent Association of the Complex with Membranes; JBC 265, pp 21749-21757, 1990.