Description
Prostate-specific antigen (PSA), also known as gamma-seminoprotein or kallikrein-3 (KLK3), is a glycoprotein enzyme encoded in humans by the KLK3 gene. It is a member of the kallikrein-related peptidase family and is secreted by the epithelial cells of the prostate gland. This gene is mapped to 19q13.33. PSA is present in small quantities in the serum of men with healthy prostates, but is often elevated in the presence of prostate cancer or other prostate disorders. It is produced for the ejaculate where it liquifies the semen in the seminal coagulum and allows sperm to swim freely. It is also believed to be instrumental in dissolving the cervical mucous cap, allowing the entry of sperm. PSA level is not a unique indicator of prostate cancer, but may also detect prostatitis or benign prostatic hyperplasia