Kininogen

Kininogens are 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.