Type II transmembrane serine protease (TTSP)

Type II transmembrane serine proteases (TTSPs) are a family of cell-surface enzymes characterized by an N-terminal intracellular domain, a single-pass transmembrane domain, and a C-terminal extracellular serine protease domain [NIH, 2009; NIH, 2021]. Transmembrane protease serine 2 (TMPRSS2) is the most prominent member of this family, particularly known for its role in facilitating the entry of coronaviruses, such as SARS-CoV-2 and MERS-CoV, and influenza viruses by cleaving and "priming" viral glycoproteins [NIH, 2022; NIH, 2023]. The family is divided into four subfamilies—Hepsin/TMPRSS, Matriptase, HAT/DESC, and Corin—each with distinct tissue distributions and substrate specificities [NIH, 2021]. Beyond viral infection, TTSPs like TMPRSS2 and matriptase are involved in physiological processes such as tissue homeostasis and signaling, but their dysregulation is frequently linked to cancer progression, notably prostate cancer through the TMPRSS2-ERG gene fusion [Novus Bio; NIH, 2014]. In addition to viral entry, some TTSPs like TMPRSS6 play critical roles in iron homeostasis by regulating hepcidin expression [NIH, 2009]. Therapeutic strategies targeting these proteases include small-molecule inhibitors like camostat and nafamostat, which aim to block viral entry or inhibit oncogenic signaling [NIH, 2021; MDPI, 2023]. While promising, targeting TTSPs requires careful consideration of their diverse physiological roles and the potential for viruses to utilize alternative entry pathways [NIH, 2021; NIH, 2024]. The development of selective inhibitors is a major focus in the field to minimize off-target effects on these essential physiological functions [NIH, 2021].

Other names

TTSPsType II transmembrane serine protease familyTMPRSS familyHepsin/TMPRSS subfamilyTransmembrane protease serineTMPRSS2-related proteases

Inhibition of the serine protease catalytic activity, which prevents the proteolytic cleavage and activation of substrate proteins such as viral glycoproteins (e.g., SARS-CoV-2 spike protein) or host signaling molecules involved in tumor growth and metastasis.