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You are here:Home » Molecular Biology » MB-Infectious Disease » Bacillus anthracis PA (Protective Antigen), Recombinant (Anthrax) Western Blot Positive Control

Bacillus anthracis PA (Protective Antigen), Recombinant (Anthrax) Western Blot Positive


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After inhalation by mammals, Bacillus anthracis spores germinate in alveolar macrophages then migrate to lymph nodes where they multiply. The vegetative bacteria excrete the tripartite exotoxin which consists of three polypeptides: protective antigen (PA, 83kD), lethal factor (LF, 90kD) and oedma factor (OF, 89kD The two components (OF and LF) of the toxin enzymatically modify substrates within the cytosol of the mammalian cells: The OF is an adenylate cyclase that impairs the host defenses through a variety of mechanisms inhibiting phagocytosis. The LF is a zinc dependent protease that cleaves several mitogen activated protein kinase kinases (MAPKK) and causes lysis of macrophages. To intoxicate mammalian cells, the third component of the toxin PA, binds to a ubiquitously expressed cellular receptor, Tumor Endothelium Marker-8 (TEM8). Upon binding to TEM8, PA is cleaved into 20 and 63kD fragments (PA20 and PA63) by furin or furin-like proteases. PA20 dissociates into medium and allows the PA63 fragment to heptamerize and bind LF and OF of the toxin. The resulting complex of PA63 fragment with EF and/or OF binds to PA-receptor TEM8/ATR and internalized into endosomes followed by translocation of LF and OF into cytosol of the cells.
Catalog #B0003-05T2
B. anthracis PA83 is the proteolytically activated in vivo by a furinlike protease to produce releasing a 20kD fragment (PA20) from the N-terminus. The remaining 63kD portion, PA63, may oligomerize into a ring-shaped heptamer. Although the C-terminal region of both PA63 and PA83 is capable of binding to the cell receptor, cleavage of PA is an essential step in exposing the binding sites for EF and LF. Cleavage also allows the formation of the heptamer. Each heptamer attached to the surface of a cell has the ability to bind up to three molecules of LF and/or EF. The complex formed between PA heptamer and EF or LF is taken into the cell by receptor mediated endocytosis. Following endocytosis, the acidified environment within the endosome triggers the heptamer to act as a pore releasing LF or EF into the cytosol where they attack their targets. PA is one of the three protein components of anthrax toxin, protective antigen (PA) is the central moiety that mediates the entry of lethal factor and edema factor into the target cell. PA binds to the cell surface via a type I membrane protein with a von Willebrand factor A domain called anthrax toxin receptor.
SourceProduced from purified PA63 by trypsin cleavage and purified.
Molecular Weight~20kD
ApplicationsSuitable for use in Western Blot as positive control. Not suitable for ELISA or other applications where native protein is required. Other applications not tested.
Recommended DilutionsWestern Blot: 10ul/lane. SDS may crystallize in cold conditions. It should redissolve by warming before taking it from the stock. It should be heated once prior to loading on gels. If the product has been stored for several weeks, then it may be preferable to add 5ul of fresh 2x sample buffer per 10ul of the Western Blot solution prior to heating and loading on gels. This preparation is not biologically active.
Optimal dilutions to be determined by the researcher.
Storage and StabilityLyophilized powder may be stored at -20°C. Stable for 12 months at -20°C. Reconstitute with sterile ddH2O. Aliquot to avoid repeated freezing and thawing. Store at -20°C. Stable for 6 months at -20°C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap.
Molecular Weight~20kD
PurityHighly Purified (~95-98%)
FormSupplied as a liquid in SDS-PAGE sample buffer (reduced).
Important NoteThis product as supplied is intended for research use only, not for use in human, therapeutic or diagnostic applications without the expressed written authorization of United States Biological.

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