KNG1
Description
The KNG1 (kininogen 1) is a protein-coding gene located on chromosome 3.
High-molecular-weight kininogen (HMWK or HK) is a circulating plasma protein involved in initiating blood coagulation and generating the vasodilator bradykinin via the kallikrein-kinin system. HMWK remains inactive until it binds to proteins beneath an injured endothelium, initiating coagulation, or binds to intact endothelial cells or platelets for non-coagulation functions. HMWK is an alpha-globulin with six functional domains, circulating as a single-chain polypeptide of 626 amino acids. The heavy chain contains domains 1, 2, and 3; the light chain, domains 5 and 6. Domain 4 links the heavy and light chains. Each domain contributes specific functions: Domain 1 binds calcium; Domain 2 and 3 inhibit cysteine proteases; Domain 3 also facilitates platelet and endothelial cell binding; Domain 4 is involved in bradykinin generation; Domain 5 binds heparin and cells, exhibiting antiangiogenic properties and binding to negatively charged surfaces; and Domain 6 binds prekallikrein and factor XI, a histidine-rich region. HMWK is one of four proteins essential for initiating the contact activation pathway of coagulation, alongside Factor XII, Factor XI, and prekallikrein. While not enzymatically active, it acts as a cofactor for activating kallikrein and factor XII and is crucial for factor XI activation by factor XIIa.
KNG1 is also known as BDK, BK, HAE6, HK, HMWK, KNG.
