The physiological function of KLK3 is the dissolution of the coagulum, the sperm entrapping gel composed of semenogelins and fibronectin. Its proteolytic action is effective in liquefying the coagulum so that the sperm can be liberated. The activity of<unk>  is well regulated. In the<unk> , it is present as an inactive pro-form which is activated through the action of KLK2, another kallikrein-related peptidase. In the<unk> , zinc ion concentrations are ten times higher than in other bodily fluids. Zinc ions have a strong inhibitory effect on the activity of<unk>  and on that of KLK2, so that<unk>  is totally inactive. Further regulation is achieved through pH variations. Although its activity is increased by higher pH, the inhibitory effect of zinc also increases. The pH of semen is slightly alkaline and the concentrations of zinc are high. On ejaculation, semen is exposed to the acidic pH of the vagina, due to the presence of lactic acid. In fertile couples, the final vaginal pH after coitus approaches the 6-7 levels, which coincides well with reduced zinc inhibition of<unk> . At these pH levels, the reduced<unk>  activity is countered by a decrease in zinc inhibition. Thus, the coagulum is slowly liquefied, releasing the sperm in a well-regulated manner.
Prostate-specific antigen
Carcinoembryonic antigen
Alpha-fetoprotein
Carcinoembryonic antigen peptide-1
Early prostate cancer antigen-2
Mammaglobin
CA 15-3
CA19-9