Antibody and Antigen Models

The antibody is a very important component of the immune system. Antibodies recognize and bind to antigens, triggering a variety of immune responses that protect the cell from infection. Modular in design, they are composed of 2 heavy chains and 2 light chains. Each heavy chain is composed of 4 immunoglobulin folds. Each immumoglobulin fold consists of 2 flat beta sheets, held together by a covalent disulfide bond between 2 cysteine amino acids, found in one of the beta sheets. Each light chain consists of 2 immunoglobulin folds. (See Immunoglobulin Fold Mini Model.) The antigen binding site is located at the ends of these Y-shaped proteins, where immunoglobulin folds from each chain come together.

Antibodies are difficult to study as a whole because they are so flexible. In the 1960’s, however, Rodney Porter and Gerald Edelman independently determined the structure of the antibody using different techniques. They shared the 1972 Nobel Prize in Physiology or Medicine for their work.

In this plastic model, the heavy chains are colored yellow and the light chains are colored red. The carbohydrate (blue) stabilizes the heavy chains in the molecule.

Molecule of the Month

The Molecule of the Month by scientist, author and artist Dr. David Goodsell includes an introduction to the structure and function of the chosen molecule and a discussion of its relevance to human health and welfare. Molecule of the Month articles are frequently referred to by teachers, students and researchers. More...