Fig. 5A: Normal Antibody-Antigen Reaction

The Fab portion of the antibody has specificity for binding an epitope of an antigen. An epitope is the portion of an antigen - such as a few amino acids sticking out of a protein - to which the Fab portion of an antibody molecule fits. The Fc portion of an antibody 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.

Illustration of A Normal Antibody-Antigen Reaction .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