Recombinant Human CD21 Protein, CF

R&D Systems, part of Bio-Techne | Catalog # 4909-CD

R&D Systems, part of Bio-Techne
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4909-CD-050
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Key Product Details

Source

CHO

Accession #

P20023

Conjugate

Unconjugated

Applications

Binding Activity

View all CD21 Proteins and Enzymes »

Product Specifications

Source

Chinese Hamster Ovary cell line, CHO-derived human CD21 protein
Ile21-Arg971, with a C-terminal 6-His tag

Purity

>95%, by SDS-PAGE under reducing conditions and visualized by silver stain.

Endotoxin Level

<0.01 EU per 1 μg of the protein by the LAL method.

N-terminal Sequence Analysis

Ile21

Predicted Molecular Mass

105 kDa

SDS-PAGE

130-140 kDa, reducing conditions

Activity

Measured by its binding ability in a functional ELISA.
When CD21 is coated at 5 μg/mL, complement component iC3b binds with apparent KD <10 nM.

Formulation, Preparation and Storage

4909-CD
Formulation Lyophilized from a 0.2 μm filtered solution in PBS.
Reconstitution
Reconstitute at 500 μg/mL in PBS.

Reconstitution Buffer Available:
Size / Price
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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.

Background: CD21

CD21, also known as complement receptor 2 (CR2), is a 145 kDa N-glycosylated member of the RCA (regulators of complement activation) family of proteins. The complement cascade plays an important role in the innate immune system through the recognition and clearance of immune complexes and foreign particles (1). Mature human CD21 contains a 951 aa extracellular domain (ECD) with fifteen tandem SCR/SUSHI repeats, a 28 aa transmembrane segment, and a 34 aa cytoplasmic tail (2, 3). Within the ECD human CD21 shares 67% aa identity with mouse and rat CD21. Human CD21 and CD35 are encoded by two separate genes, but in mouse partially homologous proteins are alternate splice forms of one gene (4). Alternate splicing of human CD21 generates isoforms with an altered SCR8 or an insertion between SCR10 and SCR11 (5). CD21 is primarily expressed on B cells, follicular dendritic cells, and T cells. A circulating soluble form of CD21 is released by proteolytic shedding from activated B cells (6, 7). CD21 binds the complement component fragments iC3b, C3d, and C3d,g (1, 8). It forms a complex with the B cell receptor-associated CD19 molecule and lowers the threshold for B cell activation (9 - 11). CD21 can also form complexes with the complement receptor CD35/CR1 (1, 10). Mice deficient in both CD21 and CD35 exhibit normal B cell development but severely compromised germinal center development, antibody production, establishment of protective microbial immunity, and B cell tolerance to self antigens (12, 13). In mice, CD21/CD35 must additionally be present on follicular dendritic cells to mount effective humoral responses and establishment of B cell memory (14). CD21 also binds the gp350 coat protein on Epstein-Barr virus and serves as an uptake receptor for viral infection of B cells (15).

References

  1. Roozendaal, R. and M.C. Carroll (2007) Immunol. Rev. 219:157.
  2. Weis, J.J. et al. (1988) J. Exp. Med. 167:1047.
  3. Moore, M.D. et al. (1987) Proc. Natl. Acad. Sci. 84:9194.
  4. Kurtz, C.B. et al. (1990) J. Immunol. 144:3581.
  5. Barel, M. et al. (1998) Mol. Immunol. 35:1025.
  6. Masilamani, M. et al. (2003) Eur. J. Immunol. 33:2391.
  7. Sengstake, S. et al. (2006) Int. Immunol. 18:1171.
  8. Carel, J.-C. et al. (1990) J. Biol. Chem. 265:12293.
  9. Matsumoto, A.K. et al. (1991) J. Exp. Med. 173:55.
  10. Tuveson, D.A. et al. (1991) J. Exp. Med. 173:1083.
  11. Dempsey, P.W. et al. (1996) Science 271:348.
  12. Haas, K.M. et al. (2002) Immunity 17:713.
  13. Prodeus, A.P. et al. (1998) Immunity 9:721.
  14. Rossbacher, J. et al. (2006) Eur. J. Immunol. 36:2384.
  15. Tanner, J. et al. (1987) Cell 50:203.

Alternate Names

C3DR, CD21, CR2

Entrez Gene IDs

1380 (Human); 12902 (Mouse); 289395 (Rat)

Gene Symbol

CR2

UniProt

P20023 (Human)

Additional CD21 Products

Product Documents for Recombinant Human CD21 Protein, CF

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Product Specific Notices for Recombinant Human CD21 Protein, CF

For research use only

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