Antigen-binding sites

Definition

Antigen-binding sites are specific regions on an antibody molecule that interact directly with antigens. These sites determine the antibody's specificity for a particular antigen.

5 Must Know Facts For Your Next Test

1. Antigen-binding sites are located on the variable regions of both the heavy and light chains of an antibody.
2. Each antibody has at least two identical antigen-binding sites, allowing it to bind to two identical antigens simultaneously.
3. The specificity of an antigen-binding site is determined by the unique amino acid sequences in its variable region.
4. Affinity refers to the strength of binding between a single antigen-binding site and its antigen.
5. The diversity of antigen-binding sites is generated through processes such as V(D)J recombination.

Review Questions

• What determines the specificity of an antigen-binding site?
• How many identical antigen-binding sites does a typical antibody have?
• What molecular process contributes to the diversity of antigen-binding sites?

Related terms

Antibody:

A protein produced by B cells that recognizes and binds to specific antigens.

Variable Region: The part of an antibody that varies greatly among different antibodies, responsible for antigen specificity.

Epitope:

The specific part of an antigen that is recognized and bound by an antibody's antigen-binding site.