Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
The Fab region (Fragment, antigen-binding) is the part of an antibody that binds to antigens. It contains the variable regions of both the heavy and light chains of the antibody.
5 Must Know Facts For Your Next Test
The Fab region is responsible for the specificity of antibodies in recognizing antigens.
Each antibody has two Fab regions, allowing it to bind two identical or different antigens simultaneously.
The variable region within the Fab provides a unique binding site for each specific antigen.
Fab regions are produced by enzymatic cleavage of antibodies using papain enzyme.
Monoclonal antibodies, used in various therapies, are designed to have specific Fab regions targeting particular pathogens.
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Related terms
Fc Region: The part of an antibody that interacts with cell surface receptors and complement proteins.
Variable Region: Part of the antibody's structure that varies between different antibodies and determines antigen specificity.