Rituximab is a widely used monoclonal antibody drug for treating certain lymphomas and
autoimmune diseases. To understand the molecular mechanism of recognition of human
CD20 by Rituximab, we determined the crystal structure of the Rituximab Fab in complex
with a synthesized peptide comprising the CD20 epitope (residues 163-187) at 2.6-Aå
resolution. The combining site of the Fab consists of four complementarity determining
regions that form a large, deep pocket to accommodate the epitope peptide. The bound …