Myeloblastin (EC 3.4.21.76; UniProt P24158; also known as AGP7, C-ANCA antigen, Leukocyte proteinase 3, Neutrophil proteinase 4, NP-4, P29, PR-3, PR3, Wegener autoantigen) is encoded by the PRTN3 (also known as CANCA, MBN, NP4) gene (Gene ID 5657) in human. Proteinase 3 (PR3) is one of four neutral serine proteases (elastase, cathepsin G, PR3, and neutrophil serine protease 4) stored as fully processed mature enzymes in azurophil granules of human neutrophils. Instead of being targeted to granules after their synthesis, some PR3 molecules end up on the surface of neutrophil plasma membrane in either pro- or mature form. The degree of such surface expression is genetically determined, but the surface exposure and pericellular activity of PR3 around neutrophils can be further upregulated upon neutrophil priming and activation. PR3 autoantibody (anti-neutrophil cytoplasmic antibodies or ANCA) is the main pathogenic feature in patients suffering from granulomatosis with polyangiitis (GPA; formerly called Wegener granulomatosis). ANCAs are shown to activate cytokine-primed neutrophils in vitro by cross-linking surface-exposed PR3 and Fcgamma receptors. PR3 activity and/or its inactivation by alpha 1-antitrypsin/alpha-1 proteinase inhibitor (alpha1PI) varies in the human population and contributes to the risk for GPA manifestations either at onset, during relapses, or during systemic progression. PR3 is initially produced with a signal peptide sequence (a.a. 1-25), an N-terminal and a C-terminal propeptide sequence (a.a. 26-27 and 249-256, respectively), the removal of which yields the mature enzyme (a.a. 28-248).
Synonyms: Myeloblastin, AGP7, C-ANCA antigen, Leukocyte proteinase 3, Neutrophil proteinase 4, NP-4, P29, PR-3, PR3, Wegener autoantigen
Application: Western Blotting Analysis: 2 µg/mL from a representative lot detected 5 µg of purified human neutrophil PR3 under both non-reducing and reducing conditions (Courtesy of Amber Hummel, Mayo Clinic, Rochester, MN).Flow Cytometry Analysis: A representative lot detected a large population of human peripheral blood neutrophils with surface PR3. The entire population became positively stained after TNFa-stimulation (Hinkofer, L.C., et al. (2013). J. Biol. Chem. 288(37):26635-26648).Flow Cytometry Analysis: A representative lot bound immobilized recombinant human PR3 via a distinct epitope than those recognized by clone MCPR3-3 and MCPR3-7 (Cat. No. MABF973 and MABT403, respectively) as determined by FACS analysis of bead-based competition binding assay (Silva, F., et al. (2010). J. Autoimmun. 35(4) 299-308).Flow Cytometry Analysis: A representative lot bound recombinant human PR3-, but not murine PR3-, coated Talon-beads as determined by FACS analysis. (Silva, F., et al. (2010). J. Autoimmun. 35(4) 299-308).ELISA Analysis: Representative lots were immobilized on well surface and employed to capture purified human polymorphonuclear cell PR3 or recombinant human PR3 S176A mutant, followed by affinity pull-down of PR3 autoantibodies (anti-neutrophil cytoplasmic antibodies or ANCA) from patients serum samples by the captured PR3 and the subsequent detection of the bound ANCA by alkaline phosphatase-conjugated goat anti-human IgG (Silva, F., et al. (2010). J. Autoimmun. 35(4) 299-308; Sun, J., et al. (1998). J. Immunol. Methods. 211(1-2):111-123). Western Blotting Analysis: A representative lot detected an exogenously expressed S176A mutant PR3 in lysates from transfected HMC-1 human mast cells as well as purified PR3 from human polymorphonuclear cells (Sun, J., et al. (1998). J. Immunol. Methods. 211(1-2):111-123).Affinity Binding Assay: A representative lot captured a recombinant human PR3 construct proP-PR3ctp that adopts a pro-PR3 conformation and a recombinant construct DeltaPR3ctp-S195A that adopts a mature PR3 conformation with similar affinity (Hinkofer, L.C., et al. (2013). J. Biol. Chem. 288(37):26635-26648).
Other Notes: Concentration: Please refer to lot specific datasheet.