Editing Intron (section)

== Discovery and etymology ==
Introns were first discovered in protein-coding genes of [[adenovirus]],<ref>{{cite journal | vauthors = Chow LT, Gelinas RE, Broker TR, Roberts RJ | title = An amazing sequence arrangement at the 5' ends of adenovirus 2 messenger RNA | journal = Cell | volume = 12 | issue = 1 | pages = 1–8 | date = September 1977 | pmid = 902310 | doi = 10.1016/0092-8674(77)90180-5 | s2cid = 2099968 }}</ref><ref>{{cite journal | vauthors = Berget SM, Moore C, Sharp PA | title = Spliced segments at the 5' terminus of adenovirus 2 late mRNA | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 74 | issue = 8 | pages = 3171–3175 | date = August 1977 | pmid = 269380 | pmc = 431482 | doi = 10.1073/pnas.74.8.3171 | bibcode = 1977PNAS...74.3171B | doi-access = free }}</ref> and were subsequently identified in genes encoding transfer RNA and ribosomal RNA genes. Introns are now known to occur within a wide variety of genes throughout organisms, bacteria,<ref>{{cite journal | vauthors = Belfort M, Pedersen-Lane J, West D, Ehrenman K, Maley G, Chu F, Maley F | title = Processing of the intron-containing thymidylate synthase (td) gene of phage T4 is at the RNA level | journal = Cell | volume = 41 | issue = 2 | pages = 375–382 | date = June 1985 | pmid = 3986907 | doi = 10.1016/s0092-8674(85)80010-6 | s2cid = 27127017 | author-link = Marlene Belfort }}</ref> and viruses within all of the biological kingdoms.

The fact that genes were split or interrupted by introns was discovered independently in 1977 by [[Phillip Allen Sharp]] and [[Richard J. Roberts]], for which they shared the [[Nobel Prize in Physiology or Medicine]] in 1993,<ref name="NobelPR1993">{{Cite web|url=https://www.nobelprize.org/nobel_prizes/medicine/laureates/1993/press.html|title = The Nobel Prize in Physiology or Medicine 1993}}</ref> though credit was [[Nobel_Prize_controversies#Physiology_or_medicine|excluded]] for the researchers and collaborators in their labs that did the experiments resulting in the discovery, [[Susan Berget]] and [[Louise Chow]].<ref>{{cite journal |last1=Abir-Am |first1=Pnina Geraldine |author1-link=Pnina Abir-Am|date=September 2020 |title=The Women Who Discovered RNA Splicing |url=https://www.americanscientist.org/article/the-women-who-discovered-rna-splicing |journal=[[American Scientist]] |volume=108 |issue=5 |pages=298–305 |access-date=January 12, 2024}}</ref><ref>{{cite news |last=Flint |first=Anthony |date=November 8, 1993 |title=Nobel Prize in medicine brews resentment, envy |url=https://www.newspapers.com/article/the-idaho-statesman-nobel-prize-in-medic/138599232/ |work=[[The Idaho Statesman]] |access-date=January 12, 2024 |via=[[Newspapers.com]]}}</ref> The term ''intron'' was introduced by American [[biochemist]] [[Walter Gilbert]]:<ref name="Gilbert1978"/>

<blockquote>"The notion of the [[cistron]] [i.e., gene] ... must be replaced by that of a transcription unit containing regions which will be lost from the mature messenger – which I suggest we call introns (for intragenic regions) – alternating with regions which will be expressed – exons." (Gilbert 1978)</blockquote>

The term ''intron'' also refers to ''intracistron'', i.e., an additional piece of DNA that arises within a [[cistron]].<ref>{{cite journal | vauthors = Tonegawa S, Maxam AM, Tizard R, Bernard O, Gilbert W | title = Sequence of a mouse germ-line gene for a variable region of an immunoglobulin light chain | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 75 | issue = 3 | pages = 1485–1489 | date = March 1978 | pmid = 418414 | pmc = 411497 | doi = 10.1073/pnas.75.3.1485 | doi-access = free | bibcode = 1978PNAS...75.1485T }}</ref>

Although introns are sometimes called ''intervening sequences'',<ref>{{cite journal | vauthors = Tilghman SM, Tiemeier DC, Seidman JG, Peterlin BM, Sullivan M, Maizel JV, Leder P | title = Intervening sequence of DNA identified in the structural portion of a mouse beta-globin gene | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 75 | issue = 2 | pages = 725–729 | date = February 1978 | pmid = 273235 | pmc = 411329 | doi = 10.1073/pnas.75.2.725 | doi-access = free | bibcode = 1978PNAS...75..725T }}</ref> the term "intervening sequence" can refer to any of several families of internal nucleic acid sequences that are not present in the final gene product, including [[inteins]], [[untranslated region]]s (UTR), and nucleotides removed by [[RNA editing]], in addition to introns.