CD21 Protein, Human, Recombinant (His Tag)

The cluster of differentiation (CD) system is commonly used as cell markers in Immunophenotyping. Different kinds of cells in the immune system can be identified through the surface CD molecules 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 receptor 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.

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.

Measured by its binding ability in a functional ELISA. Immobilized Human CD21 His (Cat:PH52471M2) at 2 μg/ml (100 μl/well) can bind Human Annexin VI/ANXA6 His (Cat:PH50702E2), Biotinylated, the ECof Human Annexin VI/ANXA6 His, Biotinylated is 250-900 ng/mL.

Lyophilized from sterile PBS, pH 7.4. Please contact us for any concerns or special requirements. Normally 5 % - 8 % trehalose, mannitol and 0.01% Tween 80 are added as protectants before lyophilization. Please refer to the specific buffer information in the hard copy of CoA.

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.

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. Stable for 1 year at -20°C or below from date of shipment. For maximum recovery of product, centrifuge the original vial after thawing and opening the cap. For long-term storage, aliquot and store at -20°C or below. Avoid repeated freeze-thaw cycles.