Content deleted Content added
m →Trans-acting: +wl |
→Biological roles: Shift image before "In translation" subsection header to keep header aligned with its following text, improving readability. In image caption, move italics quotes inside wikilink to avoid syntax highlighting bug when editing. |
||
Line 23:
Noncoding RNAs belong to several groups and are involved in many cellular processes.<ref name="Monga">{{cite journal | vauthors = Monga I, Banerjee I | title = Computational Identification of piRNAs Using Features Based on RNA Sequence, Structure, Thermodynamic and Physicochemical Properties | journal = Current Genomics | volume = 20 | issue = 7 | pages = 508–518 | date = November 2019 | pmid = 32655289 | pmc = 7327968 | doi = 10.2174/1389202920666191129112705 }}</ref> These range from ncRNAs of central importance that are conserved across all or most cellular life through to more transient ncRNAs specific to one or a few closely related species. The more conserved ncRNAs are thought to be [[molecular fossil]]s or relics from the [[LUCA|last universal common ancestor]] and the [[RNA world hypothesis|RNA world]], and their current roles remain mostly in regulation of information flow from DNA to protein.<ref name="pmid9419222">{{cite journal | vauthors = Jeffares DC, Poole AM, Penny D | title = Relics from the RNA world | journal = Journal of Molecular Evolution | volume = 46 | issue = 1 | pages = 18–36 | date = January 1998 | pmid = 9419222 | doi = 10.1007/PL00006280 | s2cid = 2029318 | bibcode = 1998JMolE..46...18J }}</ref><ref name="pmid9419221">{{cite journal | vauthors = Poole AM, Jeffares DC, Penny D | title = The path from the RNA world | journal = Journal of Molecular Evolution | volume = 46 | issue = 1 | pages = 1–17 | date = January 1998 | pmid = 9419221 | doi = 10.1007/PL00006275 | s2cid = 17968659 | bibcode = 1998JMolE..46....1P }}</ref><ref name="pmid10497339">{{cite journal | vauthors = Poole A, Jeffares D, Penny D | title = Early evolution: prokaryotes, the new kids on the block | journal = BioEssays | volume = 21 | issue = 10 | pages = 880–889 | date = October 1999 | pmid = 10497339 | doi = 10.1002/(SICI)1521-1878(199910)21:10<880::AID-BIES11>3.0.CO;2-P | s2cid = 45607498 }}</ref>
[[Image:010 large subunit-1FFK.gif|thumb|left|Atomic structure of the 50S Subunit from
===In translation===
▲[[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 = 905–920 | date = August 2000 | pmid = 10937989 | doi = 10.1126/science.289.5481.905 | citeseerx = 10.1.1.58.2271 | bibcode = 2000Sci...289..905B }}</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}}
| |||