Serpin B9 is a protein that in humans is encoded by the SERPINB9gene.
Serpin B9 is an inhibitor of Granzyme B (GzmB). GzmB is a potent cytotoxic molecule that is secreted by cytotoxic T lymphocytes and natural killer (NK) cells to induce apoptosis in target cells during an immune response. Serpin B9, expressed in the cytosol and nucleus, thus protects from apoptosis by cytotoxic T lymphocytes and NK cells.
Serpin B9 belongs to the large superfamily of serine proteinase inhibitors (serpins), which bind to and inactivate serine proteinases.
These interactions are involved in many cellular processes, including coagulation, fibrinolysis, complement fixation, matrix remodeling, and apoptosis (Sprecher et al., 1995).[supplied by OMIM]
↑Sun J, Stephens R, Mirza G, Kanai H, Ragoussis J, Bird PI (Feb 1999). "A serpin gene cluster on human chromosome 6p25 contains PI6, PI9 and ELANH2 which have a common structure almost identical to the 18q21 ovalbumin serpin genes". Cytogenet Cell Genet. 82 (3–4): 273–7. doi:10.1159/000015118. PMID9858835. S2CID23659776.
Buzza MS, Hirst CE, Bird CH, etal. (2001). "The granzyme B inhibitor, PI-9, is present in endothelial and mesothelial cells, suggesting that it protects bystander cells during immune responses". Cell. Immunol. 210 (1): 21–9. doi:10.1006/cimm.2001.1806. PMID11485349.
Classen CF, Ushmorov A, Bird P, Debatin KM (2006). "The granzyme B inhibitor PI-9 is differentially expressed in all main subtypes of pediatric acute lymphoblastic leukemias". Haematologica. 89 (11): 1314–21. PMID15531453.
Bruneel A, Labas V, Mailloux A, etal. (2006). "Proteomics of human umbilical vein endothelial cells applied to etoposide-induced apoptosis". Proteomics. 5 (15): 3876–84. doi:10.1002/pmic.200401239. PMID16130169. S2CID26007149.