Epitope

Epitope

An epitope, also known as "antigenic determinant", is the part of a macromolecule that is recognized by the immune system, specifically by antibodies, B cells, or T cells. The part of an antibody that recognizes the epitope is called a paratope. Although epitopes are usually thought to be derived from nonself proteins, sequences derived from the host that can be recognized are also classified as epitopes.

Most epitopes recognized by antibodies or B cells can be thought of as three-dimensional surface features of an antigen molecule; these features fit precisely and thus bind to antibodies. Exceptions are linear epitopes, which are determined by the amino acid sequence (the primary structure) rather than by the 3D shape (tertiary structure) of a protein.

T cell epitopes are presented on the surface of an antigen-presenting cell, where they are bound to MHC molecules. T cell epitopes presented by MHC class I molecules are typically peptides between 8 and 11 amino acids in lengths, whereas MHC class II molecules present longer peptides, and non-classical MHC molecules also present non-peptidic epitopes such as glycolipids.

Epitopes can be mapped using protein microarrays, and with the ELISPOT or ELISA techniques.

Genetic sequences coding for epitopes that are recognised by common antibodies can be fused to genes, thus aiding further molecular characterization of the gene product.Common epitopes used for this purpose are c-myc, HA, FLAG, V5.

Epitopes are sometimes cross-reactive. This property is exploited by the immune system in regulation by anti-idiotypic antibodies (originally proposed by Nobel laureate Niels Kaj Jerne). If an antibody binds to an antigen's epitope, the paratope could become the epitope for another antibody that will then bind to it. If this second antibody is of IgM class, its binding can upregulate the immune response; if the second antibody is of IgG class, its binding can downregulate the immune response.

Intensive research is currently taking place to design reliable tools that will predict epitopes on proteins.

ee also

* Mimotope
* Epitope mapping
* Linear epitope
* Conformational epitope
* Polyclonal B cell response

Epitope databases

* [http://www.imtech.res.in/raghava/mhcbn/ MHCBN: A database of MHC/TAP binder and T-cell epitopes]
* [http://www.imtech.res.in/raghava/bcipep/ Bcipep: A database of B-cell epitopes]
* [http://www.syfpeithi.de SYFPEITHI - First online database of T cell epitopes]
* [http://www.immuneepitope.org IEDB - Database of T and B cell epitopes with annotation of recognition context - NIH funded]
* [http://www.jenner.ac.uk/AntiJen/ ANTIJEN - T and B cell epitope database at the Jenner institute, UK]
* [http://imgt.cines.fr IMGT/3Dstructure-DB - Three-dimensional structures of B and T cell epitopes with annotation of IG and TR - IMGT, Montpellier, France]

External links

* [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?highlight=epitope&rid=imm.section.335#341 Antibodies bind to conformational shapes on the surfaces of antigens (Janeway Immunobiology Section 3.8)]
* [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=imm.figgrp.340 Antigens can bind in pockets or grooves, or on extended surfaces in the binding sites of antibodies (Janeway Immunobiology Figure 3.8)]
*


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Look at other dictionaries:

  • Epitope — Épitope Un épitope, aussi appelé déterminant antigénique, est une molécule qui peut être reconnue par un paratope (partie variable d un anticorps ou d un récepteur membranaire des lymphocytes T : TCR), pour déterminer si elle appartient au… …   Wikipédia en Français

  • epitope — epitope. См. антигенная детерминанта. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • epítope — Determinante antigénico que produce la reacción específica a través de una inmunoglobulina. Está formado por un grupo de aminoácidos presentes en la superficie del antígeno. Diccionario Mosby Medicina, Enfermería y Ciencias de la Salud, Ediciones …   Diccionario médico

  • Epitope — Epitope, antigene Determinanten ⇒ Antigene …   Deutsch wörterbuch der biologie

  • epitope — [ep′i tōp΄] n. [< EPI + Gr topos, place: see TOPIC] Immunology the site on an antigen to which an antibody attaches: its structure determines the antibody for which it is a receptor …   English World dictionary

  • Épitope — Un épitope, aussi appelé déterminant antigénique, est une molécule qui peut être reconnue par un paratope (partie variable d un anticorps ou d un récepteur membranaire des lymphocytes T : TCR), pour déterminer si elle appartient au domaine… …   Wikipédia en Français

  • Epitope — Ein Epitop (auch als antigene Determinante bezeichnet) ist ein kleiner Bereich (Molekülabschnitt) eines Antigens, gegen den das Immunsystem Antikörper bildet; denn weder die Rezeptoren auf der Oberfläche von B Zellen noch die Antikörper selbst… …   Deutsch Wikipedia

  • Epitope mapping — is the process of identification and characterization of the minimum molecular structures that are able to be recognized by the Immune System elements, mainly T and B cells. A collection of in vivo and in vitro methodologies are used for epitope… …   Wikipedia

  • epitope tag — Short peptide sequence that constitutes an epitope for an existing antibody. Widely used in molecular biology to ‘tag’ transgenic proteins (as a translational fusion product) to follow their expression and fate by immunocytochemistry or Western… …   Dictionary of molecular biology

  • epitope — noun Etymology: International Scientific Vocabulary, from epi + Greek topos place Date: 1960 a molecular region on the surface of an antigen capable of eliciting an immune response and of combining with the specific antibody produced by such a… …   New Collegiate Dictionary

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