Written by the Fiveable Content Team • Last updated August 2025
Written by the Fiveable Content Team • Last updated August 2025
Definition
Variable regions are the parts of an antibody's structure that vary between different antibodies and are responsible for antigen binding. These regions determine the specificity and diversity of the immune response.
Variable regions are located on both the heavy and light chains of an antibody.
They form the antigen-binding site through hypervariable loops, also known as complementarity-determining regions (CDRs).
The specific amino acid sequence in variable regions allows antibodies to recognize a vast array of antigens.
Monoclonal antibodies have identical variable regions, while polyclonal antibodies have diverse variable regions due to their production from multiple B cells.
The genetic recombination process called V(D)J recombination is responsible for generating the diversity in variable regions.