Editing Ribosome (section)

=== Addition of translation-independent amino acids ===
Presence of a ribosome quality control protein Rqc2 is associated with mRNA-independent protein elongation.<ref>{{cite journal | vauthors = Brandman O, Stewart-Ornstein J, Wong D, Larson A, Williams CC, Li GW, Zhou S, King D, Shen PS, Weibezahn J, Dunn JG, Rouskin S, Inada T, Frost A, Weissman JS | date = November 2012 | title = A ribosome-bound quality control complex triggers degradation of nascent peptides and signals translation stress | journal = Cell | volume = 151 | issue = 5 | pages = 1042–1054 | pmid = 23178123 | pmc = 3534965 | doi = 10.1016/j.cell.2012.10.044 }}</ref><ref>{{cite journal | vauthors = Defenouillère Q, Yao Y, Mouaikel J, Namane A, Galopier A, Decourty L, Doyen A, Malabat C, Saveanu C, Jacquier A, Fromont-Racine M | date = March 2013 | title = Cdc48-associated complex bound to 60S particles is required for the clearance of aberrant translation products | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 110 | issue = 13 | pages = 5046–5051 | pmid = 23479637 | pmc = 3612664 | doi = 10.1073/pnas.1221724110 | doi-access = free | bibcode = 2013PNAS..110.5046D }}</ref> This elongation is a result of ribosomal addition (via tRNAs brought by Rqc2) of '''''CAT''' tails'': ribosomes extend the [[C-terminus|'''''C'''''-terminus]] of a stalled protein with random, translation-independent sequences of [[alanine|'''''a'''''lanines]] and [[threonine|'''''t'''''hreonines]].<ref>{{cite journal | vauthors = Shen PS, Park J, Qin Y, Li X, Parsawar K, Larson MH, Cox J, Cheng Y, Lambowitz AM, Weissman JS, Brandman O, Frost A | date = January 2015 | title = Protein synthesis. Rqc2p and 60S ribosomal subunits mediate mRNA-independent elongation of nascent chains | journal = Science | volume = 347 | issue = 6217 | pages = 75–78 | pmid = 25554787 | pmc = 4451101 | doi = 10.1126/science.1259724 | bibcode = 2015Sci...347...75S }}</ref><ref>{{cite press release |author1=Keeley, J. |author2=Gutnikoff, R. |date=2015-01-02 |df=dmy-all |title=Ribosome studies turn up new mechanism of protein synthesis |publisher=[[Howard Hughes Medical Institute]] |url=http://www.hhmi.org/news/ribosome-studies-turn-new-mechanism-protein-synthesis |access-date=2015-01-16 |url-status=live |archive-url=https://web.archive.org/web/20150112034722/http://www.hhmi.org/news/ribosome-studies-turn-new-mechanism-protein-synthesis |archive-date=2015-01-12 }}</ref>