KLKB1

KLKB1 encodes plasma prekallikrein, the zymogen precursor of plasma kallikrein, a serine protease that participates in the surface-dependent activation of blood coagulation, fibrinolysis, kinin generation, and inflammatory responses^[1][2]. Plasma kallikrein is generated through activation of prekallikrein and functions within the plasma kallikrein-kinin system, where it reciprocally activates coagulation factor XII and cleaves high-molecular-weight kininogen to release bradykinin, thereby linking coagulation and inflammatory signaling pathways^[1][2]. Mechanistically, this contact activation pathway positions KLKB1 at the interface of hemostasis, vascular permeability regulation, and innate inflammatory processes, making it an important component of protease network biology^[1][2]. Disease relevance is highlighted by the association of KLKB1 dysfunction with prekallikrein deficiency and by evidence supporting plasma kallikrein as a therapeutic target in disorders driven by excessive bradykinin production, including hereditary angioedema^[3][4]. Compared with the tissue kallikrein-related peptidases (KLKs), plasma kallikrein encoded by KLKB1 represents a distinct evolutionary lineage and performs specialized functions in blood coagulation and blood pressure regulation rather than the broader tissue-specific activities characteristic of the KLK family^[2]. Alternative transcript variants have been reported for KLKB1, although evolutionary analyses indicate that many kallikrein isoforms may lack the catalytic triad required for protease activity, emphasizing the importance of functional characterization in experimental studies^[2]. For research applications, pharmacological and genetic inhibition of plasma kallikrein provides a useful strategy for investigating contact system activation and bradykinin-mediated disease mechanisms^[1][3].