Recombinant Caspase-8 Protein

Product Discontinued

Recombinant Caspase-8 Protein Summary

• Description: Detailed Source:E. coli-derived Ser217-Asp384 (Asp285His) (p18 subunit) & Leu385-Asp479 (p10 subunit), with a C-terminal 6-His tag
  
  N-terminal Sequence Analysis: Ser217 (p18 subunit) & Leu385 (p10 subunit)
  
  SDS-PAGE18 kDa and 10 kDa, reducing conditions
• Details of Functionality: Measured by its ability to cleave a fluorogenic peptide substrate Ac-IETD-AFC. The specific activity is >1,000 pmol/min/ug, as measured under the described conditions.
• Source: E. coli
• Protein/Peptide Type: Recombinant Protein
• Gene: CASP8
• Purity: >95%, by SDS-PAGE with silver staining, under reducing conditions.
• Endotoxin Note: <1.0 EU per 1 ug of the protein by the LAL method.

Applications/Dilutions

• Theoretical MW: 14 kDa.
  Disclaimer note: The observed molecular weight of the protein may vary from the listed predicted molecular weight due to post translational modifications, post translation cleavages, relative charges, and other experimental factors.

Packaging, Storage & Formulations

• Storage: Store at -70C. Avoid freeze-thaw cycles.
• Buffer: Supplied as a 0.2 um filtered solution in HEPES, NaCl, DTT and Sucrose with BSA as a carrier protein.
• Purity: >95%, by SDS-PAGE with silver staining, under reducing conditions.

Alternate Names for Recombinant Caspase-8 Protein

• AIS
• androgen receptor
• CASP8
• Caspase8
• Caspase-8
• DHTRTFM
• Dihydrotestosterone receptorHYSP1
• HUMARA
• Mch5
• NR3C4KD
• Nuclear receptor subfamily 3 group C member 4
• SMAX1SBMA
• spinal and bulbar muscular atrophy

Background

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).

Limitations

This product is for research use only and is not approved for use in humans or in clinical diagnosis. Peptides and proteins are guaranteed for 3 months from date of receipt.

FAQs for Caspase-8 Recombinant Protein (NB705-C8-010). (Showing 1 - 1 of 1 FAQ).

1. May we ask the MW difference between the active form and the proform of Caspase 8 while performing WB?
   • In treated cells induced to undergo apoptosis, caspase-8 migrates as a 55/53 kDa (pro-form), 41/42 kDa (a cleaved/active or intermediate form), and 18 kDa (active form). The proform (55/53 kDa) is still seen in treated cells because not all cells undergo apoptosis at once.

Bioinformatics

• Gene Symbol: CASP8