Recombinant SARS-CoV2 BA.4/BA.5 RBD Alexa Fluor® 488 Protein

HEK293 human embryonic kidney cells transfected with human ACE-2 were stained with (A) Recombinant SARS-CoV-2 BA.4/BA.5 Spike RBD His-tag Alexa Fluor® 488 (Catalog # AFG11229, filled histogram) or (B) unstained (open histogram).

2 μg/lane of Recombinant SARS-CoV-2 BA.4/BA.5 Spike RBD His-tag Alexa Fluor® 488 Protein (Catalog # AFG11229) was resolved with SDS-PAGE under reducing (R) and non-reducing (NR) conditions and visualized by Coomassie® Blue staining, showing bands at 33-39 kDa.

• Applications: Bioactivity

Recombinant SARS-CoV2 BA.4/BA.5 RBD Alexa Fluor® 488 Protein Summary

• Additional Information: His-tag, Omnicron Variant
• Details of Functionality: Measured by flow cytometry for its ability to bind HEK293 human embryonic kidney cells transfected with human ACE-2 at 0.250-1.00 µg/mL (100 µL/well).
  Please Note: Optimal dilutions should be determined by each laboratory for each application.
• Source: Human embryonic kidney cell, HEK293-derived sars-cov-2 Spike RBD protein
  Arg319-Phe541 (Gly339Asp, Ser371Phe, Ser373Pro, Ser375Phe, Thr376Ala, Asp405Asn, Arg408Ser, Lys417Asn, Asn440Lys, Leu452Arg, Ser477Asn, Thr478Lys, Glu484Ala, Phe486Val, Gln498Arg, Asn501Tyr, Tyr505His), with a C-terminal 6-His tag
• Accession #: YP_009724390.1
• N-terminal Sequence: Arg319
• Structure / Form: Labeled with Alexa Fluor® 488 via amines
  Excitation Wavelength: 488 nm
  Emission Wavelength: 515–545 nm
• Protein/Peptide Type: Recombinant Proteins
• Purity: >95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.
• Endotoxin Note: <1.0 EU per 1 μg of the protein by the LAL method.

Applications/Dilutions

• Dilutions:
  • Bioactivity
• Theoretical MW: 26 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.
• SDS-PAGE: 33-39 kDa, under reducing conditions.

Packaging, Storage & Formulations

• Storage: Protect from light. Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
  • 6 months from date of receipt, -20 to -70 °C as supplied.
  • 1 month, 2 to 8 °C under sterile conditions after opening.
  • 3 months, -20 to -70 °C under sterile conditions after opening.
• Buffer: Supplied as a 0.2 μm filtered solution in PBS with BSA as a carrier protein.
• Purity: >95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.

Notes

This product is provided under an agreement between Life Technologies Corporation and R&D Systems, Inc, and the manufacture, use, sale or import of this product is subject to one or more US patents and corresponding non-US equivalents, owned by Life Technologies Corporation and its affiliates. The purchase of this product conveys to the buyer the non-transferable right to use the purchased amount of the product and components of the product only in research conducted by the buyer (whether the buyer is an academic or for-profit entity). The sale of this product is expressly conditioned on the buyer not using the product or its components (1) in manufacturing; (2) to provide a service, information, or data to an unaffiliated third party for payment; (3) for therapeutic, diagnostic or prophylactic purposes; (4) to resell, sell, or otherwise transfer this product or its components to any third party, or for any other commercial purpose. Life Technologies Corporation will not assert a claim against the buyer of the infringement of the above patents based on the manufacture, use or sale of a commercial product developed in research by the buyer in which this product or its components was employed, provided that neither this product nor any of its components was used in the manufacture of such product. For information on purchasing a license to this product for purposes other than research, contact Life Technologies Corporation, Cell Analysis Business Unit, Business Development, 29851 Willow Creek Road, Eugene, OR 97402, Tel: (541) 465-8300. Fax: (541) 335-0354.
This product is provided under an agreement between Life Technologies Corporation and R&D Systems, Inc, and the manufacture, use, sale or import of this product is subject to one or more US patents and corresponding non-US equivalents, owned by Life Technologies Corporation and its affiliates. The purchase of this product conveys to the buyer the non-transferable right to use the purchased amount of the product and components of the product only in research conducted by the buyer (whether the buyer is an academic or for-profit entity). The sale of this product is expressly conditioned on the buyer not using the product or its components (1) in manufacturing; (2) to provide a service, information, or data to an unaffiliated third party for payment; (3) for therapeutic, diagnostic or prophylactic purposes; (4) to resell, sell, or otherwise transfer this product or its components to any third party, or for any other commercial purpose. Life Technologies Corporation will not assert a claim against the buyer of the infringement of the above patents based on the manufacture, use or sale of a commercial product developed in research by the buyer in which this product or its components was employed, provided that neither this product nor any of its components was used in the manufacture of such product. For information on purchasing a license to this product for purposes other than research, contact Life Technologies Corporation, Cell Analysis Business Unit, Business Development, 29851 Willow Creek Road, Eugene, OR 97402, Tel: (541) 465-8300. Fax: (541) 335-0354.

This product is produced by and ships from R&D Systems, Inc., a Bio-Techne brand.

Alternate Names for Recombinant SARS-CoV2 BA.4/BA.5 RBD Alexa Fluor® 488 Protein

• Spike RBD

Background

SARS-CoV-2, which causes the global pandemic coronavirus disease 2019 (Covid-19), belongs to a family of viruses known as coronaviruses that also include MERS-CoV and SARS-CoV-1. Coronaviruses are commonly comprised of four structural proteins: Spike protein (S), Envelope protein (E), Membrane protein (M) and Nucleocapsid protein (N) (1). The SARS-CoV-2 S protein is a glycoprotein that mediates membrane fusion and viral entry. The S protein is homotrimeric, with each ~180-kDa monomer consisting of two subunits, S1 and S2 (2). In SARS-CoV-2, as with most coronaviruses, proteolytic cleavage of the S protein into S1 and S2 subunits is required for activation. The S1 subunit is focused on attachment of the protein to the host receptor while the S2 subunit is involved with cell fusion (3-5).  The S Protein of the SARS-CoV-2 virus, like the SARS-CoV-1 counterpart, binds a metallopeptidase, Angiotensin-Converting Enzyme 2 (ACE-2), but with much higher affinity and faster binding kinetics through the receptor binding domain (RBD) located in the C-terminal region of S1 subunit (6). It has been demonstrated that the S Protein can invade host cells through the CD147/EMMPRIN receptor and mediate membrane fusion (7, 8). Polyclonal antibodies to the RBD of the SARS-CoV-2 protein have been shown to inhibit interaction with the ACE-2 receptor, confirming RBD as an attractive target for vaccinations or antiviral therapy (9). There is also promising work showing that the RBD may be used to detect presence of neutralizing antibodies present in a patient's bloodstream, consistent with developed immunity after exposure to the SARS-CoV-2 (10). Based on amino acid (aa) sequence homology, the SARS-CoV-2 RBD has 73% identity with SARS-CoV-1 RBD, but only 22% homology with the MERS RBD. Several emerging SARS-CoV-2 genomes have been identified including the Omicron, or B.1.1.529, variant. First identified in November 2021 in South Africa, the Omicron variant quickly became the predominant SARS-CoV-2 variant and is considered a variant of concern (VOC). The Omicron variant contains 32 mutations in the S protein, 3 to 4 times more than in other SARS-CoV-2 variants, that potentially affect viral fitness and transmissibility (11). Of these mutations,15 are located in the RBD domain and allow the Omicron variant to bind ACE-2 with greater affinity and, potentially, increased transmissibility (11, 12). Several additional mutations throughout the S protein have been shown or are predicted to enhance spike cleavage and could aid transmission (13-15). The study of the Omicron variant's impact on immune escape and reduced neutralization activity to monoclonal antibodies along with an increased risk of reinfection, even among vaccinated individuals, remains ongoing (16). The BA.4/BA.5 subvariant shows faster spreading rate than the original Omicron variant..

1. Wu, F. et al. (2020) Nature 579:265.
2. Tortorici, M.A. and D. Veesler (2019) Adv. Virus Res. 105:93.
3. Bosch, B.J. et al. (2003) J. Virol. 77:8801.
4. Belouzard, S. et al. (2009) Proc. Natl. Acad. Sci. 106:5871.
5. Millet, J.K. and G.R. Whittaker (2015) Virus Res. 202:120.
6. Ortega, J.T. et al. (2020) EXCLI J. 19:410.
7. Wang, K. et al. (2020) bioRxiv https://www.biorxiv.org/content/10.1101/2020.03.14.988345v1.
8. Isabel, S. et al. (2020) Sci Rep. 10, 14031. https://doi.org/10.1038/s41598-020-70827-z.
9. Tai, W. et al. (2020) Cell. Mol. Immunol. 17:613.
10. Okba, N. M. A. et al. (2020). Emerg. Infect. Dis. https://doi.org/10.3201/eid2607.200841.
11. Shah, M. and Woo, H.G. (2021) bioRxiv https://doi.org/10.1101/2021.12.04.471200.
12. Lupala, C.S. et al. (2021) bioRxiv https://doi.org/10.1101/2021.12.10.472102.
13. Zhang, L. et al. (2020) Nat Commun. 11:6013.
14. Lasek-Nesselquist, E. et al. (2021) medRxiv https://doi.org/10.1101/2021.03.10.21253285.
15. Scheepers, C. et al. (2021) medRxiv https://doi.org/10.1101/2021.08.20.21262342.
16. Callaway, E. and Ledford, H. (2021) Nature 600:197.

Bioinformatics

• Uniprot:
  • YP_009724390.1(Rabbit)