PI-9 Antibody (6D700): sc-71897

PI-9 Antibody (6D700) is a mouse monoclonal IgG1 antibody that detects PI-9 in mouse, rat, and human samples through applications such as western blotting (WB), immunoprecipitation (IP), immunofluorescence (IF), and immunohistochemistry. Anti-PI-9 antibody (6D700) is available in a non-conjugated form, allowing for versatile experimental use. Proteinase inhibitor-9 (PI-9), also known as cytoplasmic antiproteinase 3 (CAP3), is a crucial member of the Ovalbumin family of serine proteinase inhibitors (serpins) that plays a significant role in regulating serine proteinase activity across various physiological processes. PI-9 (6D700) monoclonal antibody recognizes a protein predominantly expressed in the placenta, lung, and cytotoxic lymphocytes, where PI-9 serves as a potent inhibitor of granzyme B, a serine protease that mediates apoptosis. The inhibition of granzyme B prevents DNA degradation and protects cells from apoptosis during immune responses, especially in the context of cytotoxic lymphocyte activity. PI-9 is localized in the nuclei of human cytotoxic cells, endothelial cells, and epithelial cells, highlighting PI-9′s role in cellular protection mechanisms. Nucleocytoplasmic distribution of PI-9 is regulated by a leptomycin B-sensitive pathway, indicating a nonconventional nuclear import and export process involving the export factor CRM1. PI-9 expression is rapidly induced by estrogen and upregulated in response to inflammatory stimuli, enhancing cellular resilience against granzyme B-induced apoptosis, particularly during target cell killing. PI-9 is expressed in various human and murine tumors, underscoring PI-9′s potential relevance in cancer biology and therapeutic strategies.

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PI-9 Antibody (6D700) References:

1. Caspase-1 (interleukin-1beta-converting enzyme) is inhibited by the human serpin analogue proteinase inhibitor 9.  |  Annand, RR., et al. 1999. Biochem J. 342 Pt 3: 655-65. PMID: 10477277
2. Inhibition of neutrophil elastase by recombinant human proteinase inhibitor 9.  |  Dahlen, JR., et al. 1999. Biochim Biophys Acta. 1451: 233-41. PMID: 10556578
3. Proteinase inhibitor 9, an inhibitor of granzyme B-mediated apoptosis, is a primary estrogen-inducible gene in human liver cells.  |  Kanamori, H., et al. 2000. J Biol Chem. 275: 5867-73. PMID: 10681578
4. Nucleocytoplasmic distribution of the ovalbumin serpin PI-9 requires a nonconventional nuclear import pathway and the export factor Crm1.  |  Bird, CH., et al. 2001. Mol Cell Biol. 21: 5396-407. PMID: 11463822
5. The granzyme B inhibitor, PI-9, is present in endothelial and mesothelial cells, suggesting that it protects bystander cells during immune responses.  |  Buzza, MS., et al. 2001. Cell Immunol. 210: 21-9. PMID: 11485349
6. Blockade of the granzyme B/perforin pathway through overexpression of the serine protease inhibitor PI-9/SPI-6 constitutes a mechanism for immune escape by tumors.  |  Medema, JP., et al. 2001. Proc Natl Acad Sci U S A. 98: 11515-20. PMID: 11562487
7. A new family of 10 murine ovalbumin serpins includes two homologs of proteinase inhibitor 8 and two homologs of the granzyme B inhibitor (proteinase inhibitor 9).  |  Sun, J., et al. 1997. J Biol Chem. 272: 15434-41. PMID: 9182575
8. Human proteinase inhibitor 9 (PI9) is a potent inhibitor of subtilisin A.  |  Dahlen, JR., et al. 1997. Biochem Biophys Res Commun. 238: 329-33. PMID: 9299506
9. 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.  |  Sun, J., et al. 1998. Cytogenet Cell Genet. 82: 273-7. PMID: 9858835

The preferred PI-9 antibody is PI-9 Antibody (F-6): sc-390501.