Low Molecular Weight Kininogen (LMWK)

Low-molecular-weight kininogen is a form of kininogen, which has been identified in mice, guinea pigs, and whales. Both HMWK and LMWK contain an identical heavy chain consisting of protein domains 1, 2, and 3. However, HMWK contains a 56-kD light chain that consists of domains 5 and 6H, whereas LMWK contains a unique 4-kD light chain that consists of domain 5L. In both proteins, the heavy and light chains are linked by domain 4, which contains the bradykinin (BK) nonapeptide.

The HMW and LMW prekininogens contain 626 and 427 amino acids, respectively. They share a common signal peptide, heavy chain, and BK moiety, which consist of 18, 362, and 9 amino acids, respectively. The unique light chains of HMW and LMW prekininogens consist of 255 and 38 amino acids, respectively.