Purity: > 95% by SDS - PAGE Format: Liquid. In Phosphate Buffered Saline (pH 7.4) containing 10% glycerol. CD21, also known as complement receptor type 2 isoform 2, is an N-glycosylated member of the regulators of complement activation family of proteins. This protein is present on all mature B-cells and some T-cells and follicular dendritic cells and is released by proteolytic shedding from activated B cell. It forms a complex with the B cell receptor-associated CD19 molecule and lowers the threshold for B cell activation. It binds the complement component fragments iC3b, C3D, and C3d. Also, this protein has a function in the complement system through serving as the cellular receptor specific for ligands such as C3 and C4. Recombinant Human CD21, fused to His-tag at C-terminus, was expressed in insect cell and purified by using conventional chromatography techniques.