Transmembrane Protease, Serine 9 (TMPRSS9)

TMPRSS9 contains a predicted type II transmembrane segment, an LDLR domain, and 3 protease domains, which they called serase-1, -2, and -3. The C-terminal serase-3 domain is predicted to be catalytically inactive. TMPRSS9 shares approximately 80% amino acid identity with both mouse and rat Tmprss9, and the protease domains share 40% to 48% amino acid identity with matriptase (ST14) and matriptase-2 (TMPRSS6). Northern blot analysis detected a 5.4-kb transcript in all adult tissues examined, fetal kidney, liver, lung, and brain, and in several tumor cell lines. Minor transcripts of 3.8 and 2.4 kb were detected in adult skeletal muscle, liver, placenta, and heart. Immunofluorescence microscopy localized TMPRSS9 to the plasma membrane in COS-7 cells.