HRG: Plasma glycoprotein that binds a number of ligands such as heme, heparin, heparan sulfate, thrombospondin, plasminogen, and divalent metal ions. Binds heparin and heparin/glycosaminoglycans in a zinc-dependent manner. Binds heparan sulfate on the surface of liver, lung, kidney and heart endothelial cells. Binds to N-sulfated polysaccharide chains on the surface of liver endothelial cells. Inhibits rosette formation. Acts as an adapter protein and is implicated in regulating many processes such as immune complex and pathogen clearance, cell chemotaxis, cell adhesion, angiogenesis, coagulation and fibrinolysis. Mediates clearance of necrotic cells through enhancing the phagocytosis of necrotic cells in an heparan sulfate-dependent pathway. This process can be regulated by the presence of certain HRG ligands such as heparin and zinc ions. Binds to IgG subclasses of immunoglobins containing kappa and lambda light chains with different affinities regulating their clearance and inhibiting the formation of insoluble immune complexes. Tethers plasminogen to the cell surface. Binds T-cells and alters the cell morphology. Modulates angiogenesis by blocking the CD6-mediated antiangiongenic effect of thrombospondins, THBS1 and THBS2. Acts as a regulator of the vascular endothelial growth factor (VEGF) signaling pathway; inhibits endothelial cell motility by reducing VEGF-induced complex formation between PXN/paxillin and ILK/integrin-linked protein kinase and by promoting inhibition of VEGF-induced tyrosine phosphorylation of focal adhesion kinases and alpha-actinins in endothelial cells. Also plays a role in the regulation of tumor angiogenesis and tumor immune surveillance. Normalizes tumor vessels and promotes antitumor immunity by polarizing tumor-associated macrophages, leading to decreased tumor growth and metastasis. Defects in HRG are the cause of thrombophilia due to histidine-rich glycoprotein deficiency (THPH11). A hemostatic disorder characterized by a tendency to thrombosis.
Protein type: Secreted, signal peptide; Secreted
Cellular Component: extracellular region; vesicle
Molecular Function: serine-type endopeptidase inhibitor activity; heparin binding; protein binding; metal ion binding; cysteine protease inhibitor activity
Biological Process: heme transport; positive regulation of immune response to tumor cell; negative regulation of blood vessel endothelial cell migration; chemotaxis; response to organic cyclic substance; fibrinolysis; negative regulation of angiogenesis; negative regulation of fibrinolysis; hemostasis; regulation of gene expression; regulation of blood coagulation; angiogenesis; negative regulation of cell growth; blood coagulation; defense response to fungus
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