Human Kininogen Heavy Chain Antibody

Kininogen, also known as alpha2-thiol proteinase inhibitor, is a multi-function protein. There are two alternatively spliced forms, designated as the high molecular weight (HMW) and low MW (LMW) forms (1). The HMW form is synthesized as a 644 amino acid (aa) precursor with a signal peptide (aa 1‑18). The mature chain (aa 19‑644) is further processed into the heavy (aa 19‑380) and the light (aa 390‑644) chains. The active peptide bradykinin (aa 381‑389) is released, which has a variety of functions including muscle contraction, hypotension and inflammation. The heavy chain consists of three cystatin-like domains, which are responsible for inhibiting cysteine proteases. The light chain consists of a His-rich domain, which is associated with the clotting activity. In comparison to the HMW form, the LMW Kininogen (427 aa) has the same sequence in its heavy chain and bradykinin, but a different sequence in its light chain (aa 402‑427). The LMW form is not involved in blood clotting.