Editing Spliceosome (section)

==History==
{{see also|Splicing (genetics)}}
In 1977, work by the [[Phillip Allen Sharp|Sharp]] and [[Richard J. Roberts|Roberts]] labs revealed that genes of higher organisms are "split" or present in several distinct segments along the DNA molecule.<ref name="Berget">{{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 = 3171–5 | date = August 1977 | pmid = 269380 | pmc = 431482 | doi = 10.1073/pnas.74.8.3171 | bibcode = 1977PNAS...74.3171B | doi-access = free }}</ref><ref name="Chow">{{cite journal | vauthors = Chow LT, Roberts JM, Lewis JB, Broker TR | title = A map of cytoplasmic RNA transcripts from lytic adenovirus type 2, determined by electron microscopy of RNA:DNA hybrids | journal = Cell | volume = 11 | issue = 4 | pages = 819–36 | date = August 1977 | pmid = 890740 | doi = 10.1016/0092-8674(77)90294-X | s2cid = 37967144 }}</ref>  The coding regions of the gene are separated by [[non-coding DNA]] that is not involved in protein expression.  The split gene structure was found when adenoviral mRNAs were hybridized to endonuclease cleavage fragments of single stranded viral DNA.<ref name="Berget" />  It was observed that the mRNAs of the mRNA-DNA hybrids contained [[5']] and [[3']] tails of non-hydrogen bonded regions.  When larger fragments of viral DNAs were used, forked structures of looped out DNA were observed when hybridized to the viral mRNAs.  It was realised that the looped out regions, the [[intron]]s, are excised from the precursor mRNAs in a process Sharp named "splicing".  The split gene structure was subsequently found to be common to most [[eukaryote|eukaryotic]] genes.  [[Phillip Allen Sharp|Phillip Sharp]] and [[Richard J. Roberts]] were awarded the [https://www.nobelprize.org/prizes/medicine/1993/summary/ Nobel Prize in Medicine 1993] for the discovery of introns and the splicing process.