Olombrada, MiriamPeña, CohueRodríguez-Galán, OlgaKlingauf-Nerurkar, PurnimaPortugal-Calisto, DanielaOborská-Oplová, MichaelaAltvater, MartinGavilanes, José GMartínez-Del-Pozo, Álvarode la Cruz, JesúsGarcía-Ortega, LucíaPanse, Vikram Govind2023-02-082023-02-082020http://hdl.handle.net/10668/15496The ribotoxin α-sarcin belongs to a family of ribonucleases that cleave the sarcin/ricin loop (SRL), a critical functional rRNA element within the large ribosomal subunit (60S), thereby abolishing translation. Whether α-sarcin targets the SRL only in mature 60S subunits remains unresolved. Here, we show that, in yeast, α-sarcin can cleave SRLs within late 60S pre-ribosomes containing mature 25S rRNA but not nucleolar/nuclear 60S pre-ribosomes containing 27S pre-rRNA in vivo. Conditional expression of α-sarcin is lethal, but does not impede early pre-rRNA processing, nuclear export and the cytoplasmic maturation of 60S pre-ribosomes. Thus, SRL-cleaved containing late 60S pre-ribosomes seem to escape cytoplasmic proofreading steps. Polysome analyses revealed that SRL-cleaved 60S ribosomal subunits form 80S initiation complexes, but fail to progress to the step of translation elongation. We suggest that the functional integrity of a α-sarcin cleaved SRL might be assessed only during translation.enAttribution-NonCommercial 4.0 Internationalhttp://creativecommons.org/licenses/by-nc/4.0/Active Transport, Cell NucleusCell NucleolusCell NucleusEndoribonucleasesFungal ProteinsProtein BiosynthesisRNA, RibosomalRibosome Subunits, Large, EukaryoticRicinSaccharomyces cerevisiaeresearch article32365182open access10.1093/nar/gkaa3151362-4962PMC7293039https://academic.oup.com/nar/article-pdf/48/11/6210/33384608/gkaa315.pdfhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC7293039/pdf