The diagram shows the structure of an antibody. Describe the roles of the variable region in forming antigen binding sites.

Antigen-binding site. biochemistry. Alternative Title: antibody-combining site. (A) The hinge region of an antibody molecule opens and closes to allow better binding between the antibody and antigenic determinants on the surface of an antigen.

This variable region, composed of 110-130 amino acids, give the antibody its specificity for binding antigen. The variable region includes the ends of the light and heavy chains. ... The constant region determines the mechanism used to destroy antigen.

The paratope is the part of an antibody which recognizes an antigen, the antigen-binding site of an antibody. It is a small region (15–22 amino acids) of the antibody's Fv region and contains parts of the antibody's heavy and light chains. The part of the antigen to which the paratope binds is called an epitope.

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