Platelet Factor 4 Protein | PF4 protein

Platelet Factor 4, Human (PF4)

Cat. Num. AAA634666

• Gene Names: PF4; PF-4; CXCL4; SCYB4
• Purity: Affinity Purified; Human PF-4 is prepared from the supernatant of thrombin-activated platelets by heparin-agarose affinity chromatography (15). Purity is assessed by SDS-PAGE analysis and heparin-neutralizing activity is verified by clotting assay.
• Synonyms: Platelet Factor 4; Human (PF4); PF4 protein

• Host: Human plasma
• Purity/Purification: Affinity Purified; Human PF-4 is prepared from the supernatant of thrombin-activated platelets by heparin-agarose affinity chromatography (15). Purity is assessed by SDS-PAGE analysis and heparin-neutralizing activity is verified by clotting assay.
• Form/Format: Supplied as a liquid in 25mM HEPES pH 7.4, 2M sodium chloride.

• Extinction Coefficient: E1%1cm, 280nm=2.6, Calculated based upon amino acid sequence and molecular weight; ; Structure: Homotetramer (monomer, Mr~7800) (5-7)
• Mode of Action: Neutralizes the anticoagulant activity of heparin.
• Preparation and Storage: May be stored at 4 degree C for short-term only. For long-term storage, store at -20 degree C. Aliquots are stable for at least 6 months at -20 degree C. 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.

Related Product Information for PF4 protein

Platelet factor-4 (PF-4) is a low molecular weight, heparin-binding protein which is secreted from agonist-activated platelets (1,2). PF-4 is localized within the platelet a-granule (2) where its concentration ranges from 11.2-12.4ug per 109 platelets making it, on a molar basis, one of the most abundant proteins in the platelet (1,2). Since the relative concentration of PF-4 in platelets exceeds that of plasma by 280,000-fold (3), PF-4 levels in plasma have been utilized as a measure of platelet activation in vivo. PF-4 is secreted from platelets in complex with a high molecular weight, proteoglycan, carrier protein (4,5). Sedimentation equilibrium experiments have shown that in the absence of its proteoglycan carrier, the molecular weight of PF-4 is 27,000-29,000 (4,5). Subsequent amino acid sequencing of PF-4 revealed a molecular weight of 7,800 (6-8) indicating that native PF-4 is a homotetramer. Functionally, PF-4 neutralizes the anticoagulant activity of heparin in plasma. The heparin binding site within PF-4 is presumably located within the lysine-rich, COOH-terminal region of the molecule (6-8). Since soluble heparin is a therapeutic agent, the physiological significance of the anti-heparin activity of PF-4 is not known. However, by interacting with cell surface expressed heparin-like glycosaminoglycans on endothelial cells, PF-4 may exert its procoagulant effect (9,10). PF-4 binding to cell surface glycosaminoglycans may also be a mechanism through which PF-4 stimulates the release of histamine from basophils (11). The chemotactic activity of PF-4 toward neutrophils and monocytes (12) has also been localized to the COOH-terminal, presumed heparin-binding domain of PF-4 (13). While PF-4 is primarily a secreted protein, PF-4 binding sites on the platelet surface have been identified which may be important for platelet aggregation (14).

Product Categories/Family for PF4 protein

Molecular Biology; MB-Coagulation Factors

NCBI and Uniprot Product Information

• NCBI GI #: 4505733
• NCBI GeneID: 5196
• NCBI Accession #: NP_002610.1
• NCBI GenBank Nucleotide #: NM_002619.3
• UniProt Accession #: P02776; Q53X61; Q9UC64; Q9UC65
• Molecular Weight: 29,000
• NCBI Official Full Name: platelet factor 4
• NCBI Official Synonym Full Names: platelet factor 4
• NCBI Official Symbol: PF4
• NCBI Official Synonym Symbols: PF-4; CXCL4; SCYB4
• NCBI Protein Information: platelet factor 4; iroplact; oncostatin-A; C-X-C motif chemokine 4; chemokine (C-X-C motif) ligand 4
• UniProt Protein Name: Platelet factor 4
• Protein Family: Platelet factor
• UniProt Gene Name: PF4
• UniProt Synonym Gene Names: CXCL4; SCYB4; PF-4
• UniProt Entry Name: PLF4_HUMAN

NCBI Description

This gene encodes a member of the CXC chemokine family. This chemokine is released from the alpha granules of activated platelets in the form of a homotetramer which has high affinity for heparin and is involved in platelet aggregation. This protein is chemotactic for numerous other cell type and also functions as an inhibitor of hematopoiesis, angiogenesis and T-cell function. [provided by RefSeq, Mar 2012]

Uniprot Description

PF4: Released during platelet aggregation. Neutralizes the anticoagulant effect of heparin because it binds more strongly to heparin than to the chondroitin-4-sulfate chains of the carrier molecule. Chemotactic for neutrophils and monocytes. Inhibits endothelial cell proliferation, the short form is a more potent inhibitor than the longer form. Belongs to the intercrine alpha (chemokine CxC) family.

Protein type: Secreted, signal peptide; Chemokine; Secreted; Motility/polarity/chemotaxis; Apoptosis

Chromosomal Location of Human Ortholog: 4q12-q21

Cellular Component: extracellular space; extracellular region

Molecular Function: heparin binding; CXCR3 chemokine receptor binding; chemokine activity

Biological Process: negative regulation of cytolysis; platelet activation; leukocyte chemotaxis; cytokine and chemokine mediated signaling pathway; response to lipopolysaccharide; positive regulation of leukocyte chemotaxis; positive regulation of cAMP metabolic process; positive regulation of tumor necrosis factor production; negative regulation of megakaryocyte differentiation; regulation of cell proliferation; G-protein coupled receptor protein signaling pathway; negative regulation of angiogenesis; platelet degranulation; negative regulation of MHC class II biosynthetic process; positive regulation of transcription from RNA polymerase II promoter; immune response; positive regulation of macrophage differentiation; inflammatory response; blood coagulation