Kininogens are inhibitors of thiol proteases. Kininogen 1 plays important role in Kinin-kallikrein system. This gene is translated into High-molecular weight kininogen (HMWK) and low-molecular weight kininogen (LMWK) after alternative splicing. HMWK is produced by the liver together with prekallikrein. It acts mainly as a cofactor on coagulation and inflammation,and has no intrinsic catalytic activity. LMWK is produced locally by numerous tissues,and secreted together with tissue kallikrein.