KLK1(KALLIKREIN 1), also called KLKR, is a protein that in humans is encoded by the KLK1 gene. KLK1 is a member of the peptidase S1 family. KLK1 is a serine protease that generates Lys-bradykinin by specific proteolysis of kininogen-1. The KLK1 gene is one of the fifteen kallikrein subfamily members located in a cluster on chromosome 19 and its exact cytogenetic location is 19q13.33. The KLK1 gene contains 5 coding exons. And KLK1 is the most centromeric gene in the cluster. Mice lacking tissue kallikrein are unable to generate significant levels of kinins in most tissues and develop cardiovascular abnormalities early in adulthood despite normal blood pressure. The protein is functionally conserved in its capacity to release the vasoactive peptide, Lys-bradykinin, from low molecular weight kininogen.