Human Siglec-3/CD33 LlaMABodyTM Bivalent VHH Llama IgG2 Fusion Antibody

R&D Systems, part of Bio-Techne | Catalog # LMAB10902

Recombinant Monoclonal Antibody. Bivalent Llama VHH domain, Llama IgG2 Fusion Antibody.
R&D Systems, part of Bio-Techne
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LMAB10902-100
LMAB10902-SP
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Key Product Details

Species Reactivity

Human

Applications

Flow Cytometry

Label

Unconjugated

Antibody Source

Recombinant Monoclonal Llama VHH domain Clone # L008.2.25LL

View all Siglec-3/CD33 Antibodies »

Product Specifications

Immunogen

Mouse myeloma cell line NS0-derived human Siglec-3/CD33 protein as immunogen for bivalent Llama VHH-Llama IgG2 Fusion Antibody
Asp18-His259
Accession # AAA51948

Specificity

Clone L008.2.25LL is a bivalent Llama VHH-Llama IgG2 Fusion Antibody that detects human Siglec-3/CD33 in direct ELISAs.  Antibody construct is depicted below. Human Siglec-3/CD33 SpecificLlama VHH domainLlama Hinge Llama IgG2N-terminusC-terminus

Clonality

Monoclonal

Host

Llama

Isotype

VHH domain

Scientific Data Images

Detection of Siglec-3/CD33 in HEK293 Human Cell Line Transfected with Human Siglec-3/CD33 and eGFP by Flow Cytometry.

HEK293 human embryonic kidney cell line transfected with either (A) human Siglec-3/CD33 or (B) irrelevant protein and eGFP was stained with Llama Anti-Human Siglec-3/CD33 Llamabody Native IgG Monoclonal Antibody (Catalog # LMAB10902) followed by Goat Anti-Llama Secondary Antibody (AF011), and then Allophycocyanin-conjugated Anti-Goat IgG Tertiary Antibody (F0108). Quadrant markers were set based on secondary plus tertiary antibody staining in the absence of primary antibody. View our protocol for Staining Membrane-associated Proteins.

Applications

Application
Recommended Usage

Flow Cytometry

0.25 µg/106 cells
Sample: HEK293 Human Cell Line Transfected with Human Siglec-3/CD33 and eGFP
Please Note: Optimal dilutions of this antibody should be experimentally determined.

Formulation, Preparation, and Storage

Purification

Protein A or G purified from cell culture supernatant

Reconstitution

Reconstitute at 0.5 mg/mL in sterile PBS. For liquid material, refer to CoA for concentration.

Reconstitution Buffer Available:
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Formulation

Lyophilized from a 0.2 μm filtered solution in PBS with Trehalose. *Small pack size (SP) is supplied either lyophilized or as a 0.2 µm filtered solution in PBS.

Shipping

Lyophilized product is shipped at ambient temperature. Liquid small pack size (-SP) is shipped with polar packs. Upon receipt, store immediately at the temperature recommended below.

Stability & Storage

Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
  • 12 months from date of receipt, -20 to -70 °C as supplied.
  • 1 month, 2 to 8 °C under sterile conditions after reconstitution.
  • 6 months, -20 to -70 °C under sterile conditions after reconstitution.

Background: Siglec-3/CD33

SARS-CoV-2, which causes the global pandemic coronavirus disease 2019 (Covid-19), belongs to a family of viruses known as coronaviruses that are commonly comprised of four structural proteins: Spike protein(S), Envelope protein (E), Membrane protein (M), and Nucleocapsid protein (N) (1). SARS-CoV-2 Spike Protein (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 two distinct peptides, 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). Based on structural biology studies, the receptor binding domain (RBD), located in the C-terminal region of S1, can be oriented either in the up/standing or down/lying state (6). The standing state is associated with higher pathogenicity and both SARS-CoV-1 and MERS can access this state due to the flexibility in their respective RBDs. A similar two-state structure and flexibility is found in the SARS-CoV-2 RBD (7). Based on amino acid (aa) sequence homology, the SARS-CoV-2 S1 subunit RBD has 73% identity with the RBD of the SARS-CoV-1 S1 RBD, but only 22% homology with the MERS S1 RBD. The low aa sequence homology is consistent with the finding that SARS and MERS bind different cellular receptors (8). The S Protein of the SARS-CoV-2 virus, like the SARS-CoV-1 counterpart, binds Angiotensin-Converting Enzyme 2 (ACE2), but with much higher affinity and faster binding kinetics (9). Before binding to the ACE2 receptor, structural analysis of the S1 trimer shows that only one of the three RBD domains in the trimeric structure is in the "up" conformation. This is an unstable and transient state that passes between trimeric subunits but is nevertheless an exposed state to be targeted for neutralizing antibody therapy (10). Polyclonal antibodies to the RBD of the SARS-CoV-2 protein have been shown to inhibit interaction with the ACE2 receptor, confirming RBD as an attractive target for vaccinations or antiviral therapy (11). 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 virus (12). Lastly, it has been demonstrated the S Protein can invade host cells through the CD147/EMMPRIN receptor and mediate membrane fusion (13, 14).

References

  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. Yuan, Y. et al. (2017) Nat. Commun. 8:15092.
  7. Walls, A.C. et al. (2010) Cell 180:281.
  8. Jiang, S. et al. (2020) Trends. Immunol. https://doi.org/10.1016/j.it.2020.03.007.
  9. Ortega, J.T. et al. (2020) EXCLI J. 19:410.
  10. Wrapp, D. et al. (2020) Science 367:1260.
  11. Tai, W. et al. (2020) Cell. Mol. Immunol. https://doi.org/10.1016/j.it.2020.03.007.
  12. Okba, N. M. A. et al. (2020). Emerg. Infect. Dis. https://doi.org/10.3201/eid2607.200841.
  13. Wang, X. et al. (2020) https://doi.org/10.1038/s41423-020-0424-9.
  14. Wang, K. et al. (2020) bioRxiv https://www.biorxiv.org/content/10.1101/2020.03.14.988345v1.

Long Name

Sialic Acid Binding Ig-like Lectin 3

Alternate Names

CD33, gp67, Siglec3

Entrez Gene IDs

945 (Human); 12489 (Mouse); 102117580 (Cynomolgus Monkey)

Gene Symbol

CD33

UniProt

AAA51948

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Certificate of Analysis

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Note: Certificate of Analysis not available for kit components.

Product Specific Notices

For research use only

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