Plasma membrane-anchored serine protease that participates in proteolytic cascades of relevance for the normal physiologic function of the prostate. Androgen-induced TMPRSS2 activates several substrates that include pro-hepatocyte growth factor/HGF, the protease activated receptor-2/F2RL1 or matriptase/ST14 leading to extracellular matrix disruption (By similarity). In addition, activates trigeminal neurons and contribute to both spontaneous pain and mechanical allodynia (PubMed:25734995). (Microbial infection) Essential for spread and pathogenesis of influenza A virus (strains H1N1, H3N2 and H7N9) and is involved in proteolytic cleavage and activation of hemagglutinin (HA) protein which is essential for viral infectivity. The catalytically active form interacts with ACE2. Activated by cleavage and secreted. Larynx, trachea and bronchi, lung, prostate and kidney. Proteolytically processed; by an autocatalytic mechanism. Knockout mice show normal growth and reach normal adulthood without having abnormalities in organ histology and alteration in protein levels of prostatic secretions (PubMed:16428450). Abrogation of viral spread and protection of mice from severe pathology and death are observed after infection with influenza A virus strains H1N1 and H7N9. Belongs to the peptidase S1 family.