Kallikrein-3 (KLK3) or prostate specific antigen (PSA) is a serine protease. The protein contains a 371-residue N-terminal heavy chain, which is composed of four Apple domains. The PSA gene is localized to human chromosome 4q35. PSA is synthesized in the liver as a proenzyme known as prekallikrein. It is a key component of the kinin-generating pathways (PK system). The protein is involved in important physiological roles, such as blood pressure modulation, complement activation, and control and maintenance of inflammatory responses. KLK3b alleles are found to be associated with end-stage renal disease (ESRD) suggesting that variants in KLK3 gene might be linked with ESRD susceptibility.
SERPINA3 is also known as α-1-antichymotrypsin (ACT or AACT). The gene consists of five exons and is mapped to human chromosome 14q32.13. The protein contains 423 amino acids and belongs to the family of serpin superfamily of protease inhibitors. SERPINA3 inhibits the activity of pancreatic chymotrypsin, leukocyte, cathepsin G, mast cell chymases, human glandular, kallikrein 2 and kallikrein 3. Elevated expression of the protein has been observed in various types of carcinomas including breast carcinoma, hepatocellular carcinoma, prostate carcinoma and adenocarcinoma of the lung.
