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Title | Early Scanning of Nascent Polypeptides inside the Ribosomal Tunnel by NAC. |
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Journal, issue, pages | Mol Cell, Vol. 75, Issue 5, Page 996-1006.e8, Year 2019 |
Publish date | Sep 5, 2019 |
Authors | Martin Gamerdinger / Kan Kobayashi / Annalena Wallisch / Stefan G Kreft / Carolin Sailer / Renate Schlömer / Nadine Sachs / Ahmad Jomaa / Florian Stengel / Nenad Ban / Elke Deuerling / |
PubMed Abstract | Cotranslational processing of newly synthesized proteins is fundamental for correct protein maturation. Protein biogenesis factors are thought to bind nascent polypeptides not before they exit the ...Cotranslational processing of newly synthesized proteins is fundamental for correct protein maturation. Protein biogenesis factors are thought to bind nascent polypeptides not before they exit the ribosomal tunnel. Here, we identify a nascent chain recognition mechanism deep inside the ribosomal tunnel by an essential eukaryotic cytosolic chaperone. The nascent polypeptide-associated complex (NAC) inserts the N-terminal tail of its β subunit (N-βNAC) into the ribosomal tunnel to sense substrates directly upon synthesis close to the peptidyl-transferase center. N-βNAC escorts the growing polypeptide to the cytosol and relocates to an alternate binding site on the ribosomal surface. Using C. elegans as an in vivo model, we demonstrate that the tunnel-probing activity of NAC is essential for organismal viability and critical to regulate endoplasmic reticulum (ER) protein transport by controlling ribosome-Sec61 translocon interactions. Thus, eukaryotic protein maturation relies on the early sampling of nascent chains inside the ribosomal tunnel. |
External links | Mol Cell / PubMed:31377116 |
Methods | EM (single particle) |
Resolution | 4.2 Å |
Structure data | EMDB-4938: |
Source |
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