Recombinant Human CD20/MS4A1 Protein (Full-length, C-His)

Measured by functional ELISA / flow-based assay. The detergent-formulated full-length complex binds reference anti-CD20 antibodies rituximab and ofatumumab with EC50 values in the ng/mL range, confirming native loop conformation.

CD20 (MS4A1) is a four-pass transmembrane phosphoprotein of the MS4A family and one of the most successful B-cell surface targets in therapeutics. It is expressed from the pre-B-cell stage through mature B cells and is lost upon differentiation into plasma cells, a pattern that enables selective B-cell depletion while sparing the antibody-producing compartment. Although its precise physiological ligand remains undefined, CD20 associates with lipid rafts and regulates calcium influx, cell-cycle progression and B-cell receptor signaling. The extracellular loops carry the epitopes recognized by rituximab, ofatumumab and obinutuzumab — antibodies whose complement activation, ADCC and direct signaling have transformed the treatment of B-cell lymphomas and autoimmune disease. Because conformational anti-CD20 epitopes span membrane-proximal loops, our full-length, detergent-formulated CD20 complex preserves native geometry far better than peptide fragments, making it the format of choice for biosimilar QC, epitope binning and immunization.