The paratope is the part of an antibody

Antibody

An antibody, also known as an immunoglobulin, is a large Y-shaped protein used by the immune system to identify and neutralize foreign objects such as bacteria and viruses. The antibody recognizes a unique part of the foreign target, termed an antigen...

 which recognises an antigen

Antigen

An antigen is a foreign molecule that, when introduced into the body, triggers the production of an antibody by the immune system. The immune system will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader. These invaders can be molecules such as...

, the antigen-binding site of an antibody. It is a small region (of 15–22 amino acids) of the antibody's Fv region and contains parts of the antibody's heavy and light chains

Immunoglobulin light chain

]The immunoglobulin light chain is the small polypeptide subunit of an antibody .A typical antibody is composed of two immunoglobulin heavy chains and two Ig light chains.-In humans:...

.

The part of the antigen to which the paratope binds is called an epitope

Epitope

An epitope, also known as antigenic determinant, is the part of an antigen that is recognized by the immune system, specifically by antibodies, B cells, or T cells. The part of an antibody that recognizes the epitope is called a paratope...

. This can be mimicked by a mimotope

Mimotope

A mimotope is a macromolecule, often a peptide, which mimics the structure of an epitope. Because of this property it causes an antibody response similar to the one elicited by the epitope. An antibody for a given epitope antigen will recognize a mimotope which mimics that epitope. Mimotopes are...

. In the figure given on the right hand side, the engraved inner portions of idiotype (encircled region no.5) is the paratope where the epitope

Epitope

An epitope, also known as antigenic determinant, is the part of an antigen that is recognized by the immune system, specifically by antibodies, B cells, or T cells. The part of an antibody that recognizes the epitope is called a paratope...

of the antigen binds.