|Detection of Human and Mouse Caspase‑8 by Western Blot. Western blot shows lysates of Jurkat human leukemic T cell line and DA3 mouse myeloma cell line treated with 1 µM staurosporine for the indicated time. PVDF membrane was probed with 0.5 µg/mL Goat Anti-Human/Mouse Caspase‑8 Antigen Affinity-purified Polyclonal Antibody (Catalog # AF705) followed by HRP-conjugated Anti-Goat IgG Secondary Antibody (Catalog # HAF017). Specific bands for Caspase‑8 precursor were detected at approximately 60 kDa (as indicated in upper panal) and specific bands for cleaved Caspase-8 were detected at approximately 14 - 18 kDa (as indicated in lower panal). This experiment was conducted under reducing conditions and using Immunoblot Buffer Group 4.|
Caspase-8 (Cysteine-aspartic acid protease 8/Casp8a; also named MCH5, FLICA and MACH alpha 1) is a 28 kDa member of the peptidase C14A family of enzymes (1, 2, 3). It is widely expressed and is considered an initiating caspase for the apoptotic cascade (4). Caspase-8 acts on a wide variety of substrates, including procaspases-3, 4, 6, 7, 9 and 10, c-FLIPL and procaspase‑8 itself (1, 5, 6). Human procaspase-8a is a 54‑56 kDa, 479 amino acid (aa) protein (4, 7, 8, 9). It contains two N-terminal death domains (aa 1‑177), followed by a catalytic site that utilizes His317Gly318 plus Cys360. Normally, it is an inactive, cytosolic monomer (1, 10, 11). But following death-domain (DD) containing receptor oligomerization, Caspase-8 is recruited to the death-inducing signaling complex (DISC) that forms around the death domains of the oligomerized receptor (12). FADD/CAP-1 is recruited first, followed by procaspase-8/CAP-4 and, possibly, c-FLIPL and procaspase‑10 (12). The recruitment, or concentration, of procaspase-8 induces homodimerization. This act alone is sufficient for activation. However, the activity level is modest at best, and appears to be directed towards either itself, or c-FLIPL, which is known to form a functional heterodimer with procaspase-8 (5, 11). When directed towards itself, autocleavage occurs first between Asp374Ser375, generating a 43 kDa (p43) N-terminal (aa 1‑374) and an 11 kDa C‑terminal (aa 375‑479) fragment. The C‑terminus is further cleaved between Asp384Leu385 to generate a mature p10 subunit (aa 385‑479). The p43 subunit is next cleaved twice, once between Asp216Ser217, and again between Asp210Ser211 to generate a 26 kDa DD-containing prodomain (aa 1‑210) with an additional 18 kDa mature p18 subunit (aa 217‑374) (12). p18 and p10 noncovalently associate to form a 28 kDa heterodimer, which subsequently associates with another p18:p10 heterodimer to form an active, mature Caspase-8 molecule. This leaves the DISC to act on downstream apoptotic procaspases. In the event procaspase-8 comes to the DISC complexed with c‑FLIPL, c‑FLIPL will be cleaved by procaspase-8, generating a p43 fragment that is analogous to the Caspase-8 p43 subunit. This fragment, however, appears not to be an intermediate in a proteolytic cascade. Rather, it serves as a functional subunit, interacting with TRAF2 and activating NF kappa B. This may account for many of the nonapoptotic activities associated with Caspase-8 (5, 6, 13). Mature human and mouse Caspase-8a heterodimers are 73% aa identical (14).
R&D Systems personnel manually curate a database that contains references using R&D Systems products. The data collected includes not only links to publications in PubMed, but also provides information about sample types, species, and experimental conditions.
Showing Results 1 - 3 of 3
Filter your results:
The reconstitution calculator allows you to quickly calculate the volume of a reagent to reconstitute your vial. Simply enter the mass of reagent and the target concentration and the calculator will determine the rest.
The document you requested is not available online. Please enter the Catalog Number and Lot Number below to have a document emailed to you at the address provided