Epitope

What is an Epitope? An epitope refers to the specific target against which an individual antibody binds. When an antibody binds to a protein, it isn’t binding to the entire full-length protein. Instead, it is binding to a to a segment of that protein known as an epitope. In general, an epitope is approximately five or six amino acids in length. So, a typical full-length protein sequence actually contains many different epitopes against which antibodies can bind. And, for any given protein sequence, one will typically find that multiple unique antibodies will recognize the protein. Each of these antibodies binds to a specific epitope located on that protein. Binding between the antibody and the epitope occurs at the Antigen Binding Site, which is called a paratope and is located at the tip of the variable region on the antibody. This paratope is only capable of binding with one unique epitope. Within a protein sequence, one can find: • Continuous epitopes, which are linear sequences of amino acids • Discontinuous epitopes, which exist only when the protein is folded into a particular conformation. In the context of developing a Next:

Recent Examples on the Web All 32 antibodies competed strongly for similar S2 stem-helix epitopes, targeting a similar region containing the hydrophobic core residues of the spike fusion machinery. — William A. Haseltine, Forbes, 17 Mar. 2023 The epitope previously described is highly conserved across betacoronaviruses. — William A. Haseltine, Forbes, 17 Mar. 2023 Researchers analyze the sample in a lab to identify antigens and epitopes associated with various diseases. — Laura Hensley, Verywell Health, 6 Mar. 2023 More detailed analysis, including binding to an isolated peptide corresponding to this region, reveals that the antibody recognizes a linear epitope. — William A. Haseltine, Forbes, 23 Dec. 2021 B cells respond most strongly when each arm attaches to a different epitope. — Jon Cohen, Science | AAAS, 15 Apr. 2021 Soon activists could talk about viral assays, reverse transcription, cytokine regulation, epitope mapping. — Caren Cooper, Discover Magazine, 21 July 2014 The most prevalent mutation in this T cell epitope is an amino acid substitution of proline for leucine, denoted as YLQLRTFLL or P272L mutation. — William A. Haseltine, Forbes, 17 Aug. 2022 One potential benefit might be longer-lasting protection, Greenberger speculated, since the coronavirus is unlikely to mutate every protein epitope included in this vaccine. — Angus Chen, STAT, 14 Apr. 2022 See More These examples are programmatically compiled from various online sources to illustrate current usage ...

By Reginald Davey Reviewed by The understanding of disease requires knowledge of specific biological structures present in disease-causing organisms. This knowledge informs the effective development of preventive treatments and vaccines. This article will explain what one of these structures, the epitope, is and how mapping it is important for medical science. Image Credit: DariaRen/Shutterstock.com The epitope An epitope is the part of an antigen that the host’s immune system recognizes, eliciting the immune response to an invading pathogen. It specifically binds to the corresponding antigen receptor on the immune cell (such as a B cell) and binding only occurs if the structures are complementary. Once epitope and receptor bind together in this puzzle-like combination, the production of antibodies is stimulated. These antibodies are specifically targeted to the epitopes that bind to the antigen receptors. In this manner, the epitope is also the region of the antigen that is recognized by the specific antibody which then removes the antigen from the host organism after binding to it. The region on the antibody which binds to the epitope is known as the paratope. Many The epitope is also referred to as the antigenic determinant. It is usually a non-self protein. However, in the case of autoimmune diseases, sequences in the host can be recognized as epitopes by the immune system. Epitopes are generally around five or six amino acids in length. Types of epitope There are thre...

\( \newcommand\) • • • • Learning Objectives • Define antigen and immunogen. • State what antigens are composed of chemically. • List 3 characteristics an antigen must have to be immunogenic. • Define epitope. • Briefly describe how the body recognizes an antigen as foreign. • Compare B-cell receptors and T-cell receptors in terms of how they recognize epitopes. • In terms of infectious diseases, list 2 categories of microbial materials that may act as an antigen. • List 3 groups of noninfectious materials that may act as an antigen. • Define the following: • endogenous antigen • exogenous antigen • autoantigen • hapten An antigen is defined as a substance that reacts with antibody molecules and antigen receptors on lymphocytes. An immunogen is an antigen that is recognized by the body as non-self and stimulates an adaptive immune response. For simplicity, both antigens and immunogens are usually referred to as antigens. To be immunogenic, an antigen must possess three characteristics: • be of high molecular weight, • exhibit chemical complexity, and • exhibit foreignness (recognized as non-self by the body). Chemically, antigens are large molecular weight proteins (including conjugated proteins such as glycoproteins, lipoproteins, and nucleoproteins) and polysaccharides (including lipopolysaccharides). These protein and polysaccharide antigens are found on the surfaces of viruses and cells, including microbial cells (bacteria, fungi, protozoans) and human cells. Epitopes ...

When an antibody binds to an antigen, it isn’t binding to the entire antigen but to a segment of that antigen known as an epitope. The part of an epitope is called a paratope​. Paratope is located at the tip of the variable region of an immunoglobulin, in its antigen-binding site. This paratope is only capable of binding with one unique epitope. B cells can recognize an epitope alone but T cells can recognize an epitope only when it is associated with an An antigen can have one or more epitopes. Most antigens have many determinants (i.e., they are multivalent). In general, antibodies bind epitopes that are roughly five amino acids or sugars in size, whereas T-cell receptors bind epitopes between 8 and 17 amino acids in size. There may be a presence of related antigens across various species. Related antigens have some epitopes in common but some that are different. Related antigens are also referred to as cross-reacting antigens because antibodies targeted to one antigen are able to react with all other antigens carrying the same epitope. Table of Contents • • • • Functions of Epitopes Epitope recognition by B-cell and T-cell is central to humoral and cell-mediated immune response. The humoral branch (B cells) recognizes an enormous variety of epitopes (also referred to as B-cell epitopes): those displayed on the exposed regions of bacteria or viral particles, as well as those displayed on soluble proteins, glycoproteins, polysaccharides, or lipopolysaccharides that have b...

It is possible for two or more different antigens to have an epitope in common. In these cases, antibodies targeted to one antigen are able to react with all other antigens carrying the same epitope. Such antigens are known as cross-reacting antigens. This article was most recently revised and updated by