>95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.
<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 coated onto a microplate at 2 μg/mL, Recombinant Viral HCV E2 (Catalog # 9146-HC) binds with an ED50 of 0.2-1.2 µg/mL.
When Recombinant Human CD81 LEL Fc Chimera (Catalog # 9144-CD) is coated onto a microplate at 2 μg/mL, Recombinant Viral HCV E2 (Catalog # 9146-HC) binds with an ED50 of 0.2-1.2 µg/mL.
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).
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Entrez Gene IDs:
975 (Human); 12520 (Mouse); 25621 (Rat)
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