Noun, pl. kininogens
1. Proteins that are defined by their role as precursors for kinin, but that also can have additional roles. The two main types are:
- High-molecular-weight kininogen, which is produced by the liver together with prekallikrein. It acts mainly as a cofactor on coagulation and inflammation, and has no intrinsic catalytic activity. These high molecular weight kininogens are cleaved into bradykinin and kallidin by tissue and plasma kallikreins.
- Low-molecular-weight kininogen, which is produced locally by numerous tissues, and secreted together with tissue kallikrein.
They are both spliced from the same precursor. A third type, T-kininogen, is found in rats but not humans.(wikipedia.org)
2. Endogenous peptides present in most body fluids. Certain enzymes convert them to active kinins which are involved in inflammation, blood clotting, complement reactions, etc. Kininogens belong to the cystatin superfamily. They are cysteine proteinase inhibitors. High-molecular-weight kininogen (hmwk) is split by plasma kallikrein to produce bradykinin. Low-molecular-weight kininogen (lmwk) is split by tissue kallikrein to produce kallidin. (biology-online.org)
3. Any of a set of proteins defined by their primary role as precursors for kinin. (wiktionary.org)