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| Title | Polyribosomes of circular topology are prevalent in mammalian cells. |
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| Journal, issue, pages | Nucleic Acids Res, Vol. 51, Issue 2, Page 908-918, Year 2023 |
| Publish date | Jan 25, 2023 |
 Authors | Timur N Baymukhametov / Dmitry N Lyabin / Yury M Chesnokov / Ivan I Sorokin / Evgeniya V Pechnikova / Alexander L Vasiliev / Zhanna A Afonina /  |
| PubMed Abstract | Polyribosomes, the groups of ribosomes simultaneously translating a single mRNA molecule, are very common in both, prokaryotic and eukaryotic cells. Even in early EM studies, polyribosomes have been ...Polyribosomes, the groups of ribosomes simultaneously translating a single mRNA molecule, are very common in both, prokaryotic and eukaryotic cells. Even in early EM studies, polyribosomes have been shown to possess various spatial conformations, including a ring-shaped configuration which was considered to be functionally important. However, a recent in situ cryo-ET analysis of predominant regular inter-ribosome contacts did not confirm the abundance of ring-shaped polyribosomes in a cell cytoplasm. To address this discrepancy, here we analyzed the cryo-ET structure of polyribosomes in diluted lysates of HeLa cells. It was shown that the vast majority of the ribosomes were combined into polysomes and were proven to be translationally active. Tomogram analysis revealed that circular polyribosomes are indeed very common in the cytoplasm, but they mostly possess pseudo-regular structures without specific inter-ribosomal contacts. Although the size of polyribosomes varied widely, most circular polysomes were relatively small in size (4-8 ribosomes). Our results confirm the recent data that it is cellular mRNAs with short ORF that most commonly form circular structures providing an enhancement of translation. |
 External links | Nucleic Acids Res / PubMed:36583341 / PubMed Central |
| Methods | EM (subtomogram averaging) / EM (single particle) |
| Resolution | 7.7 - 16.9 Å |
| Structure data |  EMDB-15008: Subtomogram average of 80S ribosome from HeLa cell lysate  EMDB-15018: Translating 80S ribosome from HeLa cell lysate |
| Source |
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Homo sapiens (human)