U5 spliceosomal RNA

{{Infobox rfam

| Name = U5 spliceosomal RNA

| image = RF00020.jpg

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| caption = Predicted secondary structure and sequence conservation of U5

| Symbol = U5

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| Rfam = RF00020

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| RNA_type = Gene; snRNA; splicing

| Tax_domain = Eukaryota

| GO = {{GO|0000351}} {{GO|0000353}} {{GO|0005682}} {{GO|0046540}}

| SO = {{SO|0000395}}

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U5 snRNA is a small nuclear RNA (snRNA) that participates in RNA splicing as a component of the spliceosome. It forms the U5 snRNP (small nuclear ribonucleoprotein) by associating with several proteins including Prp8 - the largest and most conserved protein in the spliceosome, Brr2 - a helicase required for spliceosome activation, Snu114, and the 7 Sm proteins.{{cite journal | vauthors = Stevens SW, Barta I, Ge HY, Moore RE, Young MK, Lee TD, Abelson J | title = Biochemical and genetic analyses of the U5, U6, and U4/U6 x U5 small nuclear ribonucleoproteins from Saccharomyces cerevisiae | journal = RNA | volume = 7 | issue = 11 | pages = 1543–53 | date = November 2001 | pmid = 11720284 | pmc = 1370197 }} U5 snRNA forms a coaxially-stacked series of helices that project into the active site of the spliceosome.{{cite journal | vauthors = Nguyen TH, Galej WP, Bai XC, Savva CG, Newman AJ, Scheres SH, Nagai K | title = The architecture of the spliceosomal U4/U6.U5 tri-snRNP | journal = Nature | volume = 523 | issue = 7558 | pages = 47–52 | date = July 2015 | pmid = 26106855 | pmc = 4536768 | doi = 10.1038/nature14548 | bibcode = 2015Natur.523...47N }}{{cite journal | vauthors = Yan C, Hang J, Wan R, Huang M, Wong CC, Shi Y | title = Structure of a yeast spliceosome at 3.6-angstrom resolution | journal = Science | volume = 349 | issue = 6253 | pages = 1182–91 | date = September 2015 | pmid = 26292707 | doi = 10.1126/science.aac7629 | bibcode = 2015Sci...349.1182Y | s2cid = 22194712 }} Loop 1, which caps this series of helices, forms 4-5 base pairs with the 5'-exon during the two chemical reactions of splicing.{{cite journal | vauthors = Newman AJ, Norman C | title = U5 snRNA interacts with exon sequences at 5' and 3' splice sites | journal = Cell | volume = 68 | issue = 4 | pages = 743–54 | date = February 1992 | pmid = 1739979 | doi=10.1016/0092-8674(92)90149-7| s2cid = 3328508 }}{{cite journal | vauthors = Sontheimer EJ, Steitz JA | title = The U5 and U6 small nuclear RNAs as active site components of the spliceosome | journal = Science | volume = 262 | issue = 5142 | pages = 1989–96 | date = December 1993 | pmid = 8266094 | doi=10.1126/science.8266094| bibcode = 1993Sci...262.1989S }} This interaction appears to be especially important during step two of splicing, exon ligation.{{cite journal | vauthors = O'Keefe RT, Norman C, Newman AJ | title = The invariant U5 snRNA loop 1 sequence is dispensable for the first catalytic step of pre-mRNA splicing in yeast | journal = Cell | volume = 86 | issue = 4 | pages = 679–89 | date = August 1996 | pmid = 8752221 | doi=10.1016/s0092-8674(00)80140-3| s2cid = 17484887 | doi-access = free }}