https://wikimd.org/index.php?action=history&feed=atom&title=Junctional_diversity 2026-04-26T13:44:19Z Revision history for this page on the wiki MediaWiki 1.44.2 https://wikimd.org/index.php?title=Junctional_diversity&diff=5797928&oldid=prev 2024-05-19T19:02:46Z

<p>CSV import</p> <p><b>New page</b></p><div>[[image:Junctionaldiversity1.PNG|thumb|left]] &#039;&#039;&#039;Junctional diversity&#039;&#039;&#039; is a mechanism in the [[immune system]] that contributes to the generation of a vast repertoire of [[antibodies]] and [[T-cell receptors]]. This process occurs during the recombination of [[gene segments]] in the development of [[B cells]] and [[T cells]].<br /> <br /> == Mechanism ==<br /> Junctional diversity arises during the process of [[V(D)J recombination]], which is the rearrangement of [[variable (V)]], [[diversity (D)]], and [[joining (J) gene segments]] in the [[immunoglobulin]] and [[T-cell receptor]] genes. This recombination process is mediated by the [[RAG1]] and [[RAG2]] proteins, which introduce double-strand breaks at specific recombination signal sequences flanking the V, D, and J segments.<br /> <br /> During the joining of these segments, additional diversity is introduced at the junctions through several mechanisms:<br /> * **N-nucleotide addition**: The enzyme [[terminal deoxynucleotidyl transferase]] (TdT) adds random nucleotides to the ends of the gene segments.<br /> * **P-nucleotide addition**: Palindromic sequences are created by the asymmetric cleavage of hairpin loops formed at the coding ends.<br /> * **Exonuclease trimming**: Nucleotides may be removed from the ends of the gene segments before they are joined.<br /> <br /> These processes result in the addition or deletion of nucleotides at the junctions, creating unique sequences that contribute to the diversity of the antigen-binding sites of antibodies and T-cell receptors.<br /> <br /> == Importance ==<br /> Junctional diversity is crucial for the adaptive immune system&#039;s ability to recognize a vast array of antigens. The unique sequences generated at the junctions of V, D, and J segments allow for the production of a wide variety of antibodies and T-cell receptors, each with a different specificity. This diversity enables the immune system to respond to a multitude of pathogens and provides the basis for immunological memory.<br /> <br /> == Related Concepts ==<br /> * [[Somatic hypermutation]]<br /> * [[Class switch recombination]]<br /> * [[Antigen presentation]]<br /> * [[Major histocompatibility complex]]<br /> * [[Clonal selection theory]]<br /> <br /> == See Also ==<br /> * [[Adaptive immune system]]<br /> * [[B cell receptor]]<br /> * [[T cell receptor]]<br /> * [[Immunoglobulin gene]]<br /> <br /> == References ==<br /> {{Reflist}}<br /> <br /> == External Links ==<br /> {{Wiktionary|junctional diversity}}<br /> <br /> [[Category:Immunology]]<br /> [[Category:Genetics]]<br /> [[Category:Immune system]]<br /> <br /> {{medicine-stub}}</div>

Prab