Complementarity-determining region: Difference between revisions

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A single chain antibody fragment showing the positions of the three complementarity determining regions, CDR1, CDR2 and CDR3

Complementarity determining regions (CDR) are antibody or T cell receptor regions where the molecule compliments an antigen's conformation. Thus, CDRs determine the molecule's specificity and make contact with a specific antigen. CDR1 and CDR2 are found in the variable (V) domain, and CDR3 includes some of V, all of diverse (D) (heavy chains only) and joint (J), and some of the constant (C) domains.

A hypervariable domain, known for its unusually high level of sequence variation, exists as a flexible loop in CDR1.

External links

Complementarity+determining+regions at the U.S. National Library of Medicine Medical Subject Headings (MeSH)

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 [[Image:ScFv-rotation.gif|right|300px|thumb|A single chain antibody fragment showing the positions of the three complementarity determining regions, CDR1, CDR2 and CDR3]]
-A '''complementarity determining region''' (CDR) is a relatively short [[amino acid]] sequence in the shape of a flexible loop, found mostly in the variable (V) domains of [[antigen]] receptors (e.g. [[immunoglobulin]] and [[T cell receptor]]). The CDRs of both immunoglobulin and the T cell receptor are the parts of these molecules that determine their specificity and make contact with a specific ligand. The CDRs are the most variable part of the molecule, and contribute to the diversity of these molecules, allowing the immunoglobulin and the T cell receptor to recognize a vast repertoire of antigens.
+'''Complementarity determining regions''' (CDR) are [[antibody]] or [[T cell receptor]] ''regions'' where the molecule ''compliments'' an antigen's conformation. Thus, CDRs determine the molecule's specificity and make contact with a specific antigen. CDR1 and CDR2 are found in the variable (V) domain, and CDR3 includes some of V, all of diverse (D) (heavy chains only) and joint (J), and some of the constant (C) domains.
+A ''hypervariable'' domain, known for its unusually high level of sequence variation, exists as a flexible loop in CDR1.
-CDR1 and CDR2 are found in the variable (V) domain of an [[antigen]] receptor, and CDR3 includes some of V, all of D (heavy chains only) and J, and some of C. Since the antigen receptors are typically composed of two [[polypeptide]] chains, there is a frequency of about six CDRs for each antigen receptor that can come into contact with the antigen (each heavy and light chain contains three CDRs). A single antibody molecule has two variable domains, wherefore it contains around twelve CDRs. About sixty CDRs can be found on a pentameric [[IgM]] molecule.
-Since most sequence variation associated with immunoglobulins and T cell receptors are found in the CDRs, these regions are sometimes referred to as ''hypervariable'' domains.<ref>{{cite book | author = Abbas AK and Lichtman AH | title = Cellular and Molecular Immunology | edition = 5th ed. | publisher =  Saunders, Philadelphia |year = 2003 |isbn = 0-7216-0008-5}}</ref> Among these, CDR3 shows the greatest variability as it is encoded by a recombination of the VJ in the case of a light chain region and [[V(D)J recombination|VDJ]] in the case of heavy chain regions.
-==References==
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