Editing Regulatory sequence (section)

==Description==
<!-- NOTE: The gene structure image templates below are in a small 1x1 table so that they scroll properly on mobile and tablet screens (as of 2015) -->[[File:Gene_structure_eukaryote_2_annotated.svg|thumb|380x380px|The structure of a [[eukaryotic]] protein-coding {{if pagename|Gene=gene|other=[[w:gene|gene]]}}. [[Regulatory sequence]] controls when and where expression occurs for the [[protein coding region]] (red). [[Promoter (genetics)|Promoter]] and [[Enhancer (genetics)|enhancer]] regions (yellow) regulate the [[Transcription (genetics)|transcription]] of the gene into a pre-mRNA which is [[Post-transcriptional modification|modified]] to remove [[Intron|introns]] (light grey) and add a 5' cap and poly-A tail (dark grey). The mRNA [[5' UTR|5']] and [[3' UTR|3']] untranslated regions (blue) regulate [[Translation (biology)|translation]] into the final protein product.<ref name="ShafeeLowe2017">{{cite journal |last1=Shafee |first1=Thomas |last2=Lowe |first2=Rohan |year=2017 |title=Eukaryotic and prokaryotic gene structure |journal=WikiJournal of Medicine |volume=4 |issue=1 |doi=10.15347/wjm/2017.002 |issn=2002-4436 |doi-access=free}}</ref>]]
In [[DNA]], regulation of [[gene]] expression normally happens at the level of RNA biosynthesis ([[Transcription (genetics)|transcription]]). It is accomplished through the sequence-specific binding of proteins ([[transcription factors]]) that activate or inhibit transcription. Transcription factors may act as [[Activator (genetics)|activators]], [[repressors]], or both. Repressors often act by preventing [[RNA polymerase]] from forming a productive complex with the transcriptional initiation region ([[Promoter (genetics)|promoter]]), while activators facilitate formation of a productive complex. Furthermore, DNA motifs have been shown to be predictive of epigenomic modifications, suggesting that transcription factors play a role in regulating the [[epigenome]].<ref>Whitaker JW, Zhao Chen, Wei Wang. (2014) Predicting the Human Epigenome from DNA Motifs. Nature Methods. doi:10.1038/nmeth.3065</ref>
[[File:Gene_structure_prokaryote_2_annotated_(hyperlinked).svg|thumb|384x384px|The structure of a [[prokaryotic]] [[operon]] of protein-coding genes. [[Regulatory sequence]] controls when expression occurs for the multiple [[Protein coding region|protein coding regions]] (red). [[Promoter (genetics)|Promoter]], [[Operator (genetics)|operator]] and [[Enhancer (genetics)|enhancer]] regions (yellow) regulate the [[Transcription (genetics)|transcription]] of the gene into an mRNA. The mRNA [[Untranslated region|untranslated regions]] (blue) regulate [[Translation (biology)|translation]] into the final protein products.]]
In [[RNA]], regulation may occur at the level of protein biosynthesis ([[Translation (biology)|translation]]), RNA cleavage, [[RNA splicing]], or transcriptional termination. Regulatory sequences are frequently associated with [[messenger RNA]] (mRNA) molecules, where they are used to control mRNA biogenesis or translation. A variety of biological molecules may bind to the RNA to accomplish this regulation, including proteins (e.g., translational repressors and splicing factors), other RNA molecules (e.g., [[MicroRNA|miRNA]]) and [[small molecules]], in the case of [[riboswitches]].