Fig. 12: Structure of the Antibody IgG


The Fab portion of the antibody has specificity for binding an epitope of an antigen. The Fc portion directs the biological activity of the antibody. In the case of IgG, the Fc portion can bind to phagocytes for enhanced attachment (opsonization) as well as activate the classical complement pathway. Antibodies are composed of 4 protein chains: 2 identical heavy chains and 2 identical light chains. Disulfide (S-S) bonds join the protein chains together.

Illustration of the Structure of the Antibody IgG .jpg by Gary E. Kaiser, Ph.D.
Professor of Microbiology, The Community College of Baltimore County, Catonsville Campus
This work is licensed under a Creative Commons Attribution 4.0 International License.
Based on a work at https://cwoer.ccbcmd.edu/science/microbiology/index_gos.html.

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Last updated: August, 2019
Please send comments and inquiries to Dr. Gary Kaiser