HPRG: Proteins and Enzymes

HPRG (Histidine-Proline-rich Glycoprotein) is a novel member of the Cystatin superfamily of cysteine proteinase inhibitors. It is a circulating glycoprotein, 67kDa in size with multiple modules. N-terminally, there are two Cystatin-like domains that interact with the immune system. C-terminally, there is one His-Pro-rich domain that is flanked by two Pro-rich segments. The Pro-rich regions bind Plasminogen while the His-Pro module binds heparan under low pH conditions. It shows anti-angiogenic and anti-fibrinolytic activity.