Reviews
WU Cai-Ping, LIU Xin, LI Qing-Wei, WANG Ji-Hong
Chinese Journal of Biochemistry and Molecular Biol.
2012, 28(1):
1-8.
Histidine-rich glycoprotein (HRG) is a plasma glycoprotein which has a multidomain structure. HRG interacts with many ligands, and regulates numerous biological functions. The ligands of HRG include Zn2+, heparin and heparan sulphate, plasminogen, plasmin, fibrinogen, thrombospondin, tropomyosin, IgG, FcγR, and complement. The binding of histidine-rich region(HRR) and ligand is enhanced when exposured to Zn2+ or low pH, and conditions associated with the sites of tissue injury or tumor growth. The properties of multidomain structure and diverse ligand binding indicates that it can act as an extracellular adaptor protein, binding with different ligands mainly on cell surfaces. Besides cell surface molecules, HRG can differentially tag at IgG, preventing generation of insoluble immune complexes. HRG binds to most cells primarily via heparan sulfate proteoglycans, in the condition of elevated free Zn2+ levels or low pH. Previous studies have showed that HRG can enhance clearance of apoptotic and necrotic phagocytes as well as immune complexes. The antiangiogenetic properties of HRG are well established in vitro and in vivo. HRG can modulate other physiological processes such as cell adhesion and migration, fibrinolysis and coagulation, complement activation. In this review, we focus on the progress of study on the structure, function and clinical research of HRG.