Human embryonic kidney cell, HEK293-derived sars-cov-2 ORF8 protein Phe16-Ile121(L84S), with a C-terminal 6-His tag
>95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.
<1.0 EU per 1 μg of the protein by the LAL method.
N-terminal sequence Analysis
Predicted Molecular Mass
18-24 kDa, under reducing conditions
Formulation, Preparation and Storage
What does CF mean?
CF stands for Carrier Free (CF). We typically add Bovine Serum Albumin (BSA) as a carrier protein to our
Adding a carrier protein enhances protein stability, increases shelf-life, and allows the recombinant
protein to be stored at a more dilute concentration.
The carrier free version does not contain BSA.
What formulation is right for me?
In general, we advise purchasing the recombinant protein with BSA for use in cell or tissue culture, or
as an ELISA standard.
In contrast, the carrier free protein is recommended for applications, in which the presence of BSA
Supplied as a 0.2 μm filtered solution in Tris and NaCl.
The product is shipped with dry ice or equivalent. Upon receipt, store it immediately at the temperature recommended below.
Stability & Storage:
Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
6 months from date of receipt, -20 to -70 °C as supplied.
3 months, -20 to -70 °C under sterile conditions after opening.
Open Reading Frame 8 (ORF8) is one of eight accessory proteins encoded at the 3' region of the coronavirus (CoV) genome (1). The accessory proteins are largely dispensable for viral replication and growth in vitro (2,3). Although not essential for replication the accessory proteins are thought to modulate virus-host interactions that are important during infection (4). Coronaviruses include various highly pathogenic strains such as SARS-CoV, MERS-CoV and SARS-CoV2 that have had significant impact on humans as well as strains that have negatively impacted livestock. ORF8 from SARS-CoV2 is a small 121 amino acid (aa) protein that can form both a monomeric or dimeric structure, the latter linked by an intermolecular disulfide bridge (5). SARS-CoV2 ORF8 contains an N-terminal signal peptide for ER import followed by an Ig-like fold. It contains two novel dimer interfaces unique to only the most recent ancestors in bats (6). SARS-CoV2 ORF8 has less than 20% sequence identity to ORF8 from SARS-CoV making it remarkably divergent. Within the ER, ORF8 is known to interact with several host proteins including factors in ERAD (7), but it is thought that ORF8 is secreted rather than retained in the ER given that ORF8 antibodies are a principal marker of SARS-CoV2 infection (8). The ORF8 protein has two high-frequency, reversible mutations including L84S (9). The L84S mutation is thought to confer instability and may disfavor SARS-CoV2 (9). While expression is not essential for replication, two separate deletions have previously been correlated with milder disease and lower hypoxia (10, 11). ORF8 has been shown to disrupt IFN-I signaling when overexpressed (12) and to down-regulate MHC-I in cells by targeting it for lysosomal degradation conferring an ability to evade immune surveillance (13).
Hartenian, E. et al. (2020) J. Biol. Chem. 295:12910.
Haijema, B.J. et al. (2004) J. Virol. 78:3863.
Yount, B. et al. (2005) J. Virol. 79:14909.
Liu, D.X. et al. (2014) Antiviral Res. 109:97.
Flower, T.G. et al. (2021) Proc. Natl. Acad. Sci. USA 118:e2021785118.
Tan, Y. et al. (2020) mBio. 11:e00760.
Gordon, D.E. et al. (2020) Nature. 583:459.
Hachim, A. et al. (2020) Nat. Immunol. 21:1293.
Wang, R. et al. (2020) Res. Sq. doi: 10.21203/rs.3.rs-49671/v1.
Muth, D. et al. (2018) Sci. Rep. 8:15177.
Young, B.E. et al. (2020) Lancet. 396:603.
Li, J.Y. et al. (2020) Virus Res. 286:198074.
Zhang, Y. et al. (2020) bioRxiv doi.org/10.1101/2020.05.24.111823.
Entrez Gene IDs
3200424 (HCoV-HKU1); 43740577 (SARS-CoV-2)
Citations for Recombinant SARS-CoV-2 ORF8 His-tag Protein, CF
Which Brands are Currently Available on bio‑techne.com? R&D Systems, Tocris Bioscience and ProteinSimple branded products are available to purchase through bio‑techne.com. ProteinSimple branded instruments are available to quote. ACD branded products will be available on bio‑techne.com in the near future. Novus Biologicals branded products are not currently available on bio‑techne.com and can be found at novusbio.com.
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