Histidine Rich Glycoprotein (HRG)

This histidine-rich glycoprotein contains two cystatin-like domains and is located in plasma and platelets. The physiological function has not been determined but it is known that the protein binds heme, dyes and divalent metal ions. It can inhibit rosette formation and interacts with heparin, thrombospondin and plasminogen. Two of the protein's effects, the inhibition of fibrinolysis and the reduction of inhibition of coagulation, indicate a potential prothrombotic effect. Mutations in this gene lead to thrombophilia due to abnormal histidine-rich glycoprotein levels.This 'histidine-rich region' in the C terminus shows a high degree of similarity to the histidine-rich region of high molecular weight kininogen (HMWK); the N terminus shares sequence similarity with antithrombin III (AT3).