Protective antigen

Mature form that oligomerizes and forms a pore to translocate the enzymatic toxin components edema factor (EF) and lethal factor (LF) into the host cytosol (PubMed:15243628, PubMed:15326297). Following attachment to host cell receptors and cleavage by FURIN, homooligomerizes to form ring-shaped oligomers that are in a pre-pore conformation, and associates with EF and LF (PubMed:10085027, PubMed:12117959, PubMed:15313199). Toxin-leaded complexes are then endocytosed in a clathrin-dependent process, followed by a conformational change of oligomerized PA-63 from the pre-pore to pore state, which is triggered by the low pH in the endosome (PubMed:10085027, PubMed:12551953, PubMed:20221438, PubMed:15326297). Once active, the pore mediates unfolding of EF and LF, which pass through the pore and translocate into the host cytosol (PubMed:16051798, PubMed:21037566, PubMed:32047164, PubMed:32810181, PubMed:32521227). Protective antigen constitutes one of the three proteins composing the anthrax toxin; it mediates attachment to host cells and translocation of edema factor (EF) and lethal factor (LF) into the host cytoplasm (PubMed:11700562, PubMed:14507921, PubMed:15243628, PubMed:15326297). PA associated with LF forms the lethal toxin (LeTx) and causes death when injected; PA associated with EF forms the edema toxin (EdTx) and produces edema (PubMed:1651334). PA induces immunity to infection with anthrax (PubMed:11544370). Mediates the attachment to host cells by binding host cell receptors ANTXR1 and ANTXR2 (PubMed:11700562, PubMed:14507921, PubMed:15243628, PubMed:15326297). Following host cell surface attachment, PA is cleaved by FURIN to generate the PA-63 (Protective antigen PA-63) form, which constitutes the mature form of the protein that oligomerizes and forms a pore to translocate the enzymatic toxin components edema factor (EF) and lethal factor (LF) into the host cytosol (PubMed:11700562, PubMed:15243628, PubMed:15326297).