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Human CD21 / CR2 / C3DR Protein (His Tag)

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Human CD21 Protein Product Information
Synonym:CR2, RP11-78B10.1, C3DR, CD21, SLEB9
Protein Construction:A DNA sequence encoding the human CD21 isoform A (P20023-1) extracellular domain (Met 1-Arg 971) was expressed, with a carboxy-terminal polyhistidine tag.
Expressed Host:Human Cells
Shipping:In general, recombinant proteins are provided as lyophilized powder which are shipped at ambient temperature.
Bulk packages of recombinant proteins are provided as frozen liquid. They are shipped out with blue ice unless customers require otherwise.
Human CD21 Protein QC Testing
Purity:> 95 % as determined by SDS-PAGE
Bio-Activity:Measured by its binding ability in a functional ELISA . Immobilized human CD21 at 2 μg/ml (100 μl/well) can bind biotinylated human CD9. The EC50 of biotinylated human CD9 is 1.76 μg/ml.
Endotoxin:< 1.0 EU per μg of the protein as determined by the LAL method
Stability:Samples are stable for up to twelve months from date of receipt at -70℃
Predicted N Terminal:Ile 21
Molecule Mass:The secreted recombinant human CD21 pro form consists of 962 amino acids with the predicted molecular mass of 106 kDa. As a result of glycosylation, the apparent molecular mass of rhCD21 is approximately 110-120 kDa in SDS-PAGE under reducing conditions.
Formulation:Lyophilized from sterile PBS, pH 7.4
1. Normally 5 % - 8 % trehalose and mannitol are added as protectants before lyophilization. Specific concentrations are included in the hardcopy of COA.
2. Please contact us for any concerns or special requirements.
Human CD21 Protein Usage Guide
Storage:Store it under sterile conditions at -20℃ to -80℃. It is recommended that the protein be aliquoted for optimal storage. Avoid repeated freeze-thaw cycles.
Reconstitution:A hardcopy of COA with reconstitution instruction is sent along with the products. Please refer to it for detailed information.
Other CD21 Recombinant Protein Products
CD21 Background

The cluster of differentiation (CD) system is commonly used as cell markers in immunophynotyping. Different kinds of cells in the immune system can be identified through the surface CD molecules which associating with the immune function of the cell. There are more than 320 CD unique clusters and subclusters have been identified. Some of the CD molecules serve as receptors or ligands important to the cell through initiating a signal cascade which then alter the behavior of the cell. Some CD proteins do not take part in cell signal process but have other functions such as cell adhesion. CD21, also known as Complement component (3d / Epstein Barr virus) receptor 2 and CR2, is a member of the CD system and is a protein involved in complement system. CD21 is present on all mature B-cells and some T-cells and follicular dendritic cells. CD21 on mature B-cells form a complex called the B cell receptor complex with two other membrane proteins, CD19 and CD81. CD21 has a function in the complement system through serving as the cellular receper specific for ligands such as C3 and C4 which can be attached to foreign macromolecules in order to remove or uptake them. This results in B-cells having enhanced response to the antigen.

Human CD21 References
  • Zola H, et al. (2007) CD molecules 2006-human cell differentiation molecules. J Immunol Methods. 318 (1-2): 1-5.
  • Ho IC, et al. (2009) GATA3 and the T-cell lineage: essential functions before and after T-helper-2-cell differentiation. Nat Rev Immunol. 9 (2): 125-35.
  • Matesanz-Isabel J, et al. (2011) New B-cell CD molecules. Immunology Letters.134 (2): 104-12.
  • Joseph M, et al. (1989) Structure and Function of the Complement Receptors, CR1 (CD35) and CR2 (CD21). Advanced in immunology. 46: 183-219.
  • Aubry JP, et al. (1992) CD21 is a ligand for CD23 and regulates IgE production. Nature 358: 505 - 7.
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    Catalog: 10811-H08H-50
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