Explore Prolytix’s high-quality platelet alpha-granule proteins—essential for coagulation, wound healing, and research. Discover their unique functions, purity, and custom options for your scientific needs.
Platelets are small (1 – 2 micron) cell fragments released from bone marrow megakaryocytes into the blood (1). Their primary function is to stop bleeding by adhering to sites of vascular injury which leads to their activation and formation of a platelet plug. Activated platelets also help to stabilize the platelet plug by providing an appropriate membrane surface for assembly and function of the coagulation enzyme complexes that lead to fibrin formation. Furthermore, upon activation, platelets release proteins and molecules that support hemostasis and promote wound healing from alpha-granules (1).
Prolytix provides several high-quality platelet alpha-granule proteins for coagulation and other research. These proteins are isolated from thrombin-activated, human platelet releasates through a variety of protein fractionation and chromatography methods. Protein purity and function are assessed by SDS-PAGE (Figure 1) and appropriate activity assays. Custom formulations, modifications and conjugations are available. The platelet alpha-granule proteins currently available from Prolytix are summarized below.
Human platelet factor-4 (Catalog # HPF4-0180) is a low molecular weight, heparin-binding protein found in platelet alpha-granules where its concentration ranges from 11.2-12.4 µg per 109 platelets (3). Functional platelet factor-4 is a homotetramer and neutralizes the anticoagulant activity of heparin in plasma. Human platelet factor-4 is highly immunogenic and plays a central role in heparin-induced thrombocytopenia.
Human platelet osteonectin (Catalog # HON-0303) is homologous to bone osteonectin but differs in collagen binding capacity due to differences in glycosylation (2). A small portion of the released osteonectin is expressed on the activated platelet cell surface (2). Platelet osteonectin is a multifunctional protein that mediates platelet adhesion and aggregation and plays a role in wound healing.
Human β-thromboglobulin (Catalog # HBTG-0210) is an alpha-granular protein like platelet factor-4 that can be used as a clinical biomarker of platelet activation. β-thromboglobulin exhibits a lower affinity for heparin than platelet factor-4 and is present at 8.1-24.2 µg per 109 platelets (3). Besides its role as a marker of platelet activation, β-thromboglobulin is involved in platelet activation, inflammation, and tissue repair.
Human thrombospondin (Catalog # HCTP-0200) is a high-molecular weight (450 kDa), heparin-binding glycoprotein and is one of the most abundant proteins in the platelet alpha-granule at 30-50 µg per 109 platelets (3). The binding of thrombospondin to the surface of both resting and thrombin-activated platelets via a specific membrane receptor has been reported (4) suggesting that it plays a role in platelet adherence and thrombus formation (5). It has also been shown to regulate extracellular matrix remodeling, inhibit angiogenesis and modulate immune and inflammatory responses.
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