Editing Non-coding RNA (section)

===Chromosome structure===

[[Telomerase]] is an RNP [[enzyme]] that adds specific [[DNA]] sequence repeats ("TTAGGG" in vertebrates) to [[telomere|telomeric]] regions, which are found at the ends of eukaryotic [[chromosomes]]. The telomeres contain condensed DNA material, giving stability to the chromosomes. The enzyme is a [[reverse transcriptase]] that carries [[Vertebrate telomerase RNA|Telomerase RNA]], which is used as a template when it elongates telomeres, which are shortened after each [[cell cycle|replication cycle]].

[[Xist]] (X-inactive-specific transcript) is a long ncRNA gene on the [[X chromosome]] of the [[Eutheria|placental mammals]] that acts as major effector of the [[X inactivation|X chromosome inactivation]] process forming [[Barr body|Barr bodies]]. An [[antisense RNA]], [[X-inactivation#Xist and Tsix RNAs|Tsix]], is a negative regulator of Xist. X chromosomes lacking Tsix expression (and thus having high levels of Xist transcription) are inactivated more frequently than normal chromosomes.  In [[drosophila|drosophilids]], which also use an [[XY sex-determination system]], the [[Drosophila roX RNA|roX]] (RNA on the X) RNAs are involved in dosage compensation.<ref name="pmid12446910">{{cite journal | vauthors = Park Y, Kelley RL, Oh H, Kuroda MI, Meller VH | title = Extent of chromatin spreading determined by roX RNA recruitment of MSL proteins | journal = Science | volume = 298 | issue = 5598 | pages = 1620–1623 | date = November 2002 | pmid = 12446910 | doi = 10.1126/science.1076686 | s2cid = 27167367 | bibcode = 2002Sci...298.1620P }}</ref>  Both Xist and roX operate by [[epigenetics|epigenetic]] regulation of transcription through the recruitment of [[Histone-Modifying Enzymes|histone-modifying enzymes]].