Complementarity determining regions (
CDRs) are part of the variable chains in
immunoglobulins (antibodies) and
T cell receptors, generated by
B-cells and
T-cells respectively, where these molecules bind to their specific antigen. A set of CDRs constitutes a
paratope. As the most variable parts of the molecules, CDRs are crucial to the diversity of antigen specificities generated by
lymphocytes.