Recombinant Human CD81 LEL Fc Chimera Protein, CF

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Recombinant Human CD81 LEL Fc Chimera Protein Bioactivity
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Recombinant Human CD81 LEL Fc Chimera Protein, CF Summary

Product Specifications

>95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.
Endotoxin Level
<0.10 EU per 1 μg of the protein by the LAL method.
Measured by its binding ability in a functional ELISA. When Recombinant Human CD81 LEL Fc Chimera is used at 2 μg/mL, Recombinant Viral HCV E2 (Catalog # 9146-HC) binds with an ED50 of 0.2-1.2 µg/mL.
Chinese Hamster Ovary cell line, CHO-derived human CD81 protein
MD Human IgG1

Human CD81 LEL
Accession # P60033

N-terminus C-terminus
Accession #
N-terminal Sequence
Structure / Form
Disulfide-linked homodimer
Predicted Molecular Mass
36 kDa
36-41 kDa, reducing conditions

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Product Datasheets

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Carrier Free

What does CF mean?

CF stands for Carrier Free (CF). We typically add Bovine Serum Albumin (BSA) as a carrier protein to our recombinant proteins. 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 could interfere.


Formulation Lyophilized from a 0.2 μm filtered solution in PBS.
Reconstitution Reconstitute at 100 μg/mL in PBS.
Shipping The product is shipped at ambient temperature. Upon receipt, store it 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.
  • 3 months, -20 to -70 °C under sterile conditions after reconstitution.

Data Image

Bioactivity Recombinant Human CD81 LEL Fc Chimera Protein Bioactivity View Larger

When Recombinant Human CD81 LEL Fc Chimera (Catalog # 9144-CD) is used at 2 µg/mL, Recombinant Viral HCV E2 (Catalog # 9146-HC) binds with an ED50 of 0.2-1.2 µg/mL.

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Background: CD81

CD81, also known as TAPA-1 and Tetraspanin-28, is an approximately 25 kDa palmitoylated component of plasma membrane lipid rafts (1). It contains four transmembrane segments, two extracellular loops of 30 and 90 amino acids (aa), and three short cytoplasmic regions (2, 3). Within the large extracellular loop, human CD81 shares 90% and 84% aa sequence identity with mouse and rat CD81, respectively. CD81 associates with a wide range of membrane proteins including CD151, TfR2, LDL R, PCSK9, Glypican 3, IFITM1, IGSF8/CD316, FPRP, and complexes of CD19-CD21 (4-11). It is required for the development of CD4+CD8+ DP thymocytes (12) and hepatocyte infection by Plasmodium sporozoites (13). It also supports B cell receptor signaling (11), Hepcidin expression (5), monocyte and B cell tethering to the vascular endothelium (14), and the immunosuppressive function of Treg and MDSC (15). CD81 additionally functions as a receptor for the E2 glycoprotein of hepatitis C virus (16). The CD81-E2 interaction inhibits NK cell cytolytic activity, provides a co-stimulatory signal to T cells, and inhibits the maturation of plasmacytoid dendritic cells (17-19).

  1. Charrin, S. et al. (2014) J. Cell Sci. 127:3641.
  2. Oren, R. et al. (1990) Mol. Cell. Biol. 10:4007.
  3. Levy, S. et al. (1991) J. Biol. Chem. 266:14597.
  4. Zhu, Y.-Z. et al. (2012) Virology 429:112.
  5. Chen, J. and C.A. Enns (2015) J. Biol. Chem. 290:7841.
  6. Le, Q.-T. et al. (2015) J. Biol. Chem. 290:23385.
  7. Takahashi, S. et al. (1990) J. Immunol. 145:2207.
  8. Stipp, C.S. et al. (2001) J. Biol. Chem. 276:40545.
  9. Stipp, C.S. et al. (2001) J. Biol. Chem. 276:4853.
  10. Liu, B. et al. (2009) Am. J. Pathol. 175:717.
  11. Cherukuri, A. et al. (2004) J. Immunol. 279:31973.
  12. Boismenu, R. et al. (1996) Science 271:198.
  13. Silvie, O. et al. (2003) Nat. Med. 9:93.
  14. Feigelson, S.W. et al. (2003) J. Biol. Chem. 278:51203.
  15. Vences-Catalan, F. et al. (2015) Cancer Res. 75:4517.
  16. Pileri, P. et al. (1998) Science 282:938.
  17. Crotta, S. et al. (2002) J. Exp. Med. 195:35.
  18. Tseng, C.-T. and G.R. Klimpel (2002) J. Exp. Med. 195:43.
  19. Tu, Z. et al. (2013) Cell. Immunol. 284:98.
Entrez Gene IDs
975 (Human); 12520 (Mouse); 25621 (Rat)
Alternate Names
CD81 antigen (target of antiproliferative 1); CD81 antigen; CD81 molecule; CD81; CVID6; TAPA1; TAPA-1; Target of the antiproliferative 1; Tetraspanin-28; TSPAN28; Tspan-28; tspan-28,26 kDa cell surface protein TAPA-1; TSPAN28S5.7


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