Anti-Human CD20 Antibody

Antibody 2H7 reacts with CD20, an ~35 kDa non-glycosylated type 1 transmembrane protein in the MS4A protein family. The CD20 polypeptide transverses the cell membrane four times, with only a minor portion of the protein displayed on the cell surface. The epitope recognized by antibody 2H7 has been mapped to the amino acid sequence YNCEPANPSEKNSPST, located in the large extracellular loop of CD20. CD20 is expressed on pre-B cells, resting and activated B cells, some follicular dendritic cells, and a subset of T cells. Expression by B cells is lost upon their differentiation into plasma cells. By associating with several proteins, including the B cell receptor (CD79), MHC class I and II, CD53, CD81, and CD82, CD20 is involved in initiating intracellular signaling pathways that modulate the activation, proliferation, and differentiation of B cells. It is thought that CD20 forms multi-subunit ion channels that regulate calcium ion flux across the plasma membrane. Activation of CD20 is accompanied by pronounced phosphorylation of the cytoplasmic domain of the ~33 kDa apo-protein, with the appearance of 35 - 37 kDa isoforms that associate with Src family kinases such as Fyn, Lck and Lyn.