Epitope

An epitope, also know 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 term macromolecule by definition implies "large Molecule " An immune system is a collection of mechanisms within an Organism that protects against Disease by identifying and killing Pathogens and Tumor Antibodies (also known as immunoglobulins, abbreviated Ig) are Gamma globulin Proteins that are found in Blood or other Bodily B cells are Lymphocytes that play a large role in the humoral immune response (as opposed to the cell-mediated immune response, which is governed by T cells belong to a group of White blood cells known as Lymphocytes, and play a central role in Cell-mediated immunity. 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. An antigen (from antibody-generating) or immunogen is a substance that prompts the generation of Antibodies and can cause an immune response 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. A linear or a sequential epitope is an Epitope that is recognized by antibodies by its linear sequence of Amino acids or Primary structure In Chemistry, an amino acid is a Molecule containing both Amine and Carboxyl Functional groups In Biochemistry, this In Biochemistry, the primary structure of a biological molecule is the exact specification of its atomic composition and the chemical bonds connecting those atoms (including In Biochemistry and Chemistry, the tertiary structure of a Protein or any other Macromolecule is its three-dimensional structure as defined

T cell epitopes are presented on the surface of an antigen-presenting cell, where they are bound to MHC molecules. See also Antigen presentation An antigen-presenting cell ( APC) or accessory cell is a cell that displays foreign Antigen complexed The major histocompatibility complex ( MHC) is a large genomic region or Gene family found in most Vertebrates It is the most gene-dense region 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. A protein microarray, sometimes referred to as a protein binding microarray, is a piece of glass on which different molecules of Protein have been affixed at separate The Enzyme-linked immunosorbent spot ( ELISPOT) assay is a common method for monitoring immune responses in humans and animals Enzyme-Linked ImmunoSorbent Assay, also called ELISA, Enzyme ImmunoAssay or EIA, is a biochemical technique used mainly in Immunology

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). Niels Kaj Jerne, FRS ( December 23, 1911 &ndash October 7, 1994) was a Danish ( English -born Immunologist 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.

Epitope databases

External links

A mimotope is a macromolecule often a Peptide, which mimics the structure of an Epitope. 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 Medical Subject Headings ( MeSH) is a huge Controlled vocabulary (or metadata system for the purpose of indexing journal articles and books

Dictionary

-noun

(biochemistry) That part of a biomolecule (such as a protein) that is the target of an immune response

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