Small Cajal body-specific RNA

{{Infobox rfam | Name = Small Cajal body specific RNA 1 | image = RF00553.png | width = 250 | caption = Predicted secondary structure of Small Cajal body specific RNA 1 | Symbol = SCARNA1 | AltSymbols = | Rfam = RF00553 | miRBase = | miRBase_family = | RNA_type = gene, snRNA, snoRNA, scaRNA; | Tax_domain = Vertebrata | CAS_number = | EntrezGene = | HGNCid = | OMIM = | PDB = | RefSeq = | Chromosome = | Arm = | Band = | LocusSupplementaryData = }}

'''Small Cajal body-specific RNAs''' ('''scaRNAs''') are a class of small nucleolar RNAs (snoRNAs) that specifically localise to the Cajal body, a nuclear organelle (cellular sub-organelle) involved in the biogenesis of small nuclear ribonucleoproteins (snRNPs or snurps). ScaRNAs guide the modification (methylation and pseudouridylation) of RNA polymerase II transcribed spliceosomal RNAs U1, U2, U4, U5 and U12.

The first scaRNA identified was U85.<ref name="pmid11157760">{{cite journal | vauthors = Jády BE, Kiss T | title = A small nucleolar guide RNA functions both in 2′-''O''-ribose methylation and pseudouridylation of the U5 spliceosomal RNA | journal = The EMBO Journal | volume = 20 | issue = 3 | pages = 541–551 | date = February 2001 | pmid = 11157760 | pmc = 133463 | doi = 10.1093/emboj/20.3.541 }}</ref> It is unlike typical snoRNAs in that it is a composite C/D box and H/ACA box snoRNAs and can guide both pseudouridylation and 2′-''O''-methylation. Not all scaRNAs are composite C/D and H/ACA box snoRNA and most scaRNAs are structurally and functionally indistinguishable from snoRNAs, directing ribosomal RNA (rRNA) modification in the nucleolus.

== ''Drosophila'' scaRNAs == Several studies identified scaRNAs in ''Drosophila.''<ref name="pmid11157760" /><ref>{{cite journal | vauthors = Tortoriello G, Accardo MC, Scialò F, Angrisani A, Turano M, Furia M | title = A novel Drosophila antisense scaRNA with a predicted guide function | journal = Gene | volume = 436 | issue = 1–2 | pages = 56–65 | date = May 2009 | pmid = 19230845 | doi = 10.1016/j.gene.2009.02.005 }}</ref><ref>{{cite journal | vauthors = Tycowski KT, Shu MD, Kukoyi A, Steitz JA | title = A conserved WD40 protein binds the Cajal body localization signal of scaRNP particles | journal = Molecular Cell | volume = 34 | issue = 1 | pages = 47–57 | date = April 2009 | pmid = 19285445 | pmc = 2700737 | doi = 10.1016/j.molcel.2009.02.020 }}</ref><ref name=":0">{{cite journal | vauthors = Deryusheva S, Gall JG | title = Small Cajal body-specific RNAs of Drosophila function in the absence of Cajal bodies | journal = Molecular Biology of the Cell | volume = 20 | issue = 24 | pages = 5250–5259 | date = December 2009 | pmid = 19846657 | pmc = 2793299 | doi = 10.1091/mbc.E09-09-0777 }}</ref><ref name=":1">{{cite journal | vauthors = Deryusheva S, Gall JG | title = Novel small Cajal-body-specific RNAs identified in Drosophila: probing guide RNA function | journal = RNA | volume = 19 | issue = 12 | pages = 1802–1814 | date = December 2013 | pmid = 24149844 | pmc = 3884663 | doi = 10.1261/rna.042028.113 }}</ref> One of the studies showed that several ''Drosophila'' scaRNAs could function equally well in the nucleoplasm of mutant flies that lack Cajal bodies.<ref name=":0" /> Further investigation showed that scaRNA pugU6-40 targets U6 snRNA, whose modification occurs in the nucleolus not CB and that pugU1-6 and pug U2-55 guide 2 RNAs: snRNA and 28s rRNA.<ref name=":1" />

==Small Cajal body-specific RNA 1== In molecular biology, Small Cajal body-specific RNA 1 (also known as SCARNA1 or ACA35) is a small nucleolar RNA found in Cajal bodies and believed to be involved in the pseudouridylation of U2 spliceosomal RNA at residue U89.

scaRNA1 is a non-coding RNA, which are functional products of genes not translated into proteins. Such RNA molecules usually contain important secondary structure or ligand-binding motifs and are involved in many important biological processes in the cell.<ref name="darzacq_2002">{{cite journal | vauthors = Darzacq X, Jády BE, Verheggen C, Kiss AM, Bertrand E, Kiss T | title = Cajal body-specific small nuclear RNAs: a novel class of 2′-O-methylation and pseudouridylation guide RNAs | journal = The EMBO Journal | volume = 21 | issue = 11 | pages = 2746–2756 | date = June 2002 | pmid = 12032087 | pmc = 126017 | doi = 10.1093/emboj/21.11.2746 }}</ref>

scaRNA1 belongs to the H/ACA box class of snoRNAs, as it has the predicted hairpin-hinge-hairpin-tail structure, conserved H/ACA-box motifs, and is found associated with GAR1 protein.<ref name="pmid15199136">{{cite journal | vauthors = Kiss AM, Jády BE, Bertrand E, Kiss T | title = Human box H/ACA pseudouridylation guide RNA machinery | journal = Molecular and Cellular Biology | volume = 24 | issue = 13 | pages = 5797–5807 | date = July 2004 | pmid = 15199136 | pmc = 480876 | doi = 10.1128/MCB.24.13.5797-5807.2004 }}</ref>

== References == {{reflist}}

== External links == * [http://www-snorna.biotoul.fr/info.php#4 snoRNAbase: human H/ACA and C/D box snoRNA database] * {{rfam|id=RF00553|name=Small Cajal body-specific RNA}}

Category:Non-coding RNA Category:Small nuclear RNA Category:Spliceosome Category:RNA splicing