Structural highlights 
  Disease 
[KLKB1_HUMAN] Defects in KLKB1 are the cause of prekallikrein deficiency (PKK deficiency) [MIM:612423]; also known as Fletcher factor deficiency. This disorder is a blood coagulation defect. 
  Function 
[KLKB1_HUMAN] The enzyme cleaves Lys-Arg and Arg-Ser bonds. It activates, in a reciprocal reaction, factor XII after its binding to a negatively charged surface. It also releases bradykinin from HMW kininogen and may also play a role in the renin-angiotensin system by converting prorenin into renin.