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[[Image:010 large subunit-1FFK.gif|thumb|left|Atomic structure of the 50S Subunit from ''[[Haloarcula|Haloarcula marismortui]]''. Proteins are shown in blue and the two RNA strands in orange and yellow.<ref name=Ban>{{cite journal | vauthors = Ban N, Nissen P, Hansen J, Moore PB, Steitz TA | title = The complete atomic structure of the large ribosomal subunit at 2.4 A resolution | journal = Science | volume = 289 | issue = 5481 | pages = 905–20 | date = August 2000 | pmid = 10937989 | doi = 10.1126/science.289.5481.905 | bibcode = 2000Sci...289..905B | citeseerx = 10.1.1.58.2271 }}</ref> The small patch of green in the center of the subunit is the active site.]]
Many of the conserved, essential and abundant ncRNAs are involved in [[Translation (genetics)|translation]]. [[Ribonucleoprotein]] (RNP) particles called [[ribosome]]s are the 'factories' where translation takes place in the cell. The ribosome consists of more than 60% [[rRNA|ribosomal RNA]]; these are made up of 3 ncRNAs in [[prokaryotes]] and 4 ncRNAs in [[eukaryotes]]. Ribosomal RNAs catalyse the translation of nucleotide sequences to protein. Another set of ncRNAs, [[Transfer RNA]]s, form an 'adaptor molecule' between [[mRNA]] and protein. The [[snoRNA|H/ACA box and C/D box snoRNAs]] are ncRNAs found in archaea and eukaryotes. [[RNase MRP]] is restricted to eukaryotes. Both groups of ncRNA are involved in the maturation of rRNA. The snoRNAs guide covalent modifications of rRNA, tRNA and [[snRNA]]s; RNase MRP cleaves the [[internal transcribed spacer 1]] between 18S and 5.8S rRNAs. The ubiquitous ncRNA, [[RNase P]], is an evolutionary relative of RNase MRP.<ref name="PMID16540690">{{cite journal | vauthors = Zhu Y, Stribinskis V, Ramos KS, Li Y | title = Sequence analysis of RNase MRP RNA reveals its origination from eukaryotic RNase P RNA | journal = RNA | volume = 12 | issue = 5 | pages = 699–706 | date = May 2006 | pmid = 16540690 | pmc = 1440897 | doi = 10.1261/rna.2284906 }}</ref> RNase P matures tRNA sequences by generating mature 5'-ends of tRNAs through cleaving the 5'-leader elements of precursor-tRNAs. Another ubiquitous RNP called [[Signal recognition particle|SRP]] recognizes and transports specific nascent proteins to the [[endoplasmic reticulum]] in [[eukaryote]]s and the [[plasma membrane]] in [[prokaryote]]s. In bacteria, [[tmRNA|Transfer-messenger RNA]] (tmRNA) is an RNP involved in rescuing stalled ribosomes, tagging incomplete [[Peptide|polypeptides]] and promoting the degradation of aberrant mRNA.{{citation needed|date=June 2017}}
===In RNA splicing===
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