Recombinant Human CD21 Protein (His Tag)

Name: Recombinant Human CD21 Protein (His Tag)
Brand: Beta LifeScience
SKU: BLPSN-0793
Availability: InStock

Collections: Cluster of differentiation (cd) proteins, Featured cd protein molecules, Recombinant proteins

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Product Overview

Tag	His
Host Species	Human
Accession	P20023
Synonym	C3DR, CD21, CR, CVID7, SLEB9
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 32 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.
Description	A DNA sequence encoding the human CD21 isoform A (P20023-1) extracellular domain (Met 1-Arg 971) was expressed, with a carboxy-terminal His tag.
Source	HEK293
Predicted N Terminal	Ile 21
AA Sequence	Met 1-Arg 971
Molecular Weight	The secreted recombinant human CD21 pro form consists of 962 a.a. 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.
Purity	>95% as determined by SDS-PAGE
Endotoxin	< 1.0 EU per μg of the protein as determined by the LAL method
Bioactivity	Measured by its binding ability in a functional ELISA. Immobilized human CD21 at 2 ug/ml (100 ul/well) can bind biotinylated human CD9. The EC50 of biotinylated human CD9 is 1.76 ug/ml.
Formulation	Lyophilized from sterile PBS, pH 7.4.
Stability	The recombinant proteins are stable for up to 1 year from date of receipt at -70°C.
Usage	For Research Use Only
Storage	Store the protein under sterile conditions at -20°C to -80°C. It is recommended that the protein be aliquoted for optimal storage. Avoid repeated freeze-thaw cycles.

FAQs

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Proteins are sensitive to heat, and freeze-drying can preserve the activity of the majority of proteins. It improves protein stability, extends storage time, and reduces shipping costs. However, freeze-drying can also lead to the loss of the active portion of the protein and cause aggregation and denaturation issues. Nonetheless, these adverse effects can be minimized by incorporating protective agents such as stabilizers, additives, and excipients, and by carefully controlling various lyophilization conditions.

Commonly used protectant include saccharides, polyols, polymers, surfactants, some proteins and amino acids etc. We usually add 8% (mass ratio by volume) of trehalose and mannitol as lyoprotectant. Trehalose can significantly prevent the alter of the protein secondary structure, the extension and aggregation of proteins during freeze-drying process; mannitol is also a universal applied protectant and fillers, which can reduce the aggregation of certain proteins after lyophilization.

Our protein products do not contain carrier protein or other additives (such as bovine serum albumin (BSA), human serum albumin (HSA) and sucrose, etc., and when lyophilized with the solution with the lowest salt content, they often cannot form A white grid structure, but a small amount of protein is deposited in the tube during the freeze-drying process, forming a thin or invisible transparent protein layer.

Reminder: Before opening the tube cap, we recommend that you quickly centrifuge for 20-30 seconds in a small centrifuge, so that the protein attached to the tube cap or the tube wall can be aggregated at the bottom of the tube. Our quality control procedures ensure that each tube contains the correct amount of protein, and although sometimes you can't see the protein powder, the amount of protein in the tube is still very precise.

To learn more about how to properly dissolve the lyophilized recombinant protein, please visit Lyophilization FAQs.