• Purity

  >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.  

• Activity

  Measured by its binding ability in a functional ELISA. When Recombinant Human CD81 LEL Fc Chimera is coated onto a microplate at 2 μg/mL, Recombinant Viral HCV E2 (Catalog # 9146-HC) binds with an ED    ₅₀ of 0.2-1.2 µg/mL.

• Source

  Chinese Hamster Ovary cell line, CHO-derived

  MD	Human IgG1 (Pro100-Lys330)	IEGR	Human CD81 LEL (Phe113-Lys201) Accession # P60033
  N-terminus			C-terminus

• Accession #

• N-terminal Sequence    
  Analysis

  Met

• Structure / Form

  Disulfide-linked homodimer

• Predicted Molecular Mass

  36 kDa

• SDS-PAGE

  36-41 kDa, reducing conditions

Data Images

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).

• References:

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