Description
Protein S Polyclonal Antibody – HRP Conjugated – Sheep
Affinity’s Protein S Polyclonal Antibody – HRP Conjugated – Sheep is the base level of our horseradish peroxidase conjugated Protein S antibodies. The purity of IgG is typically 90% and is provided in a solution of HEPES buffered saline containing 50% glycerol (v/v). The titre is essentially the same as the starting antiserum and each vial typically contains the amount of IgG recovered from one milliliter of antiserum however this IgG has been conjugated with Horseradish Peroxidase as an enzyme reporter. This Protein S Polyclonal Antibody – HRP Conjugated – Sheep is generally intended for use as labeled primary antibodies in applications such as immunoassay and immunoblotting.
Product Code: SAPS-HRP
Retail Product Size: 0.2mg vial
Host Animal: Sheep Anti-Human Protein S Polyclonal Antibody – HRP Conjugated – Sheep
Species Cross Reactivity: View Chart
Product Datasheet: Protein S PS Polyclonal Antibody, hrp conjugated anti-human sheep IgG
Description of Protein S
Protein S 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 Review
- 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.
