A paratope, also called an antigen-binding site, is a part of an antibody which recognizes and binds to an antigen. It is a small region (of 5 to 10 amino acids) of the antibody's Fv region, part of the fragment antigen-binding (Fab region), and contains parts of the antibody's heavy and light chains. Each arm of the Y shape of an antibody monomer is tipped with a paratope, which is a set of complementarity determining regions.
The part of the antigen to which the paratope binds is called an epitope. This can be mimicked by a mimotope. The figure given on the right hand side depicts the antibody commonly found on a B leukocyte. The engraved inner portions of idiotype (encircled region no.5) is the paratope where the epitope of the antigen binds.
- Goldsby, Richard; Kindt, TJ; Osborne, BA; Kuby, Janis (2003). "Antigens (Chapter 3)". Immunology (Fifth ed.). New York: W. H. Freeman and Company. pp. 57–75. ISBN 0716749475.