Editing Spliceosome (section)

{{Short description|Molecular machine that removes intron RNA from the primary transcript}}
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A '''spliceosome''' is a large [[ribonucleoprotein]] (RNP) complex found primarily within the [[cell nucleus|nucleus]] of [[eukaryotic cells]]. The spliceosome is assembled from [[snRNA|small nuclear RNA]]s ([[snRNA]]) and numerous proteins. Small nuclear RNA (snRNA) molecules bind to specific proteins to form a small nuclear ribonucleoprotein complex (snRNP, pronounced "snurps"), which in turn combines with other snRNPs to form a large ribonucleoprotein complex called a spliceosome. The spliceosome removes [[intron]]s from a [[Transcription (genetics)|transcribed]] pre-mRNA, a type of [[primary transcript]].  This process is generally referred to as [[RNA splicing|splicing]].<ref name="Spliceosome_review_2011">{{cite journal | vauthors = Will CL, Lührmann R | title = Spliceosome structure and function | journal = Cold Spring Harbor Perspectives in Biology | volume = 3 | issue = 7 | pages = a003707 | date = July 2011 | pmid = 21441581 | pmc = 3119917 | doi = 10.1101/cshperspect.a003707 }}</ref>  An analogy is a film editor, who selectively cuts out irrelevant or incorrect material (equivalent to the [[introns]]) from the initial film and sends the cleaned-up version to the director for the final cut.{{cn|date=July 2024}}

However, sometimes the RNA within the intron acts as a ribozyme, splicing itself without the use of a spliceosome or protein enzymes.{{cn|date=November 2024}}

[[File:Spliceosome ball cycle new2.jpg|350px|thumb|right|Spliceosomal splicing cycle]]