7qwq
Ternary complex of ribosome nascent chain with SRP and NACTernary complex of ribosome nascent chain with SRP and NAC
Structural highlights
FunctionSRP19_HUMAN Signal-recognition-particle assembly, binds directly to 7S RNA and mediates binding of the 54 kDa subunit of the SRP. Publication Abstract from PubMedThe nascent polypeptide-associated complex (NAC) interacts with newly synthesized proteins at the ribosomal tunnel exit and competes with the signal recognition particle (SRP) to prevent mistargeting of cytosolic and mitochondrial polypeptides to the endoplasmic reticulum (ER). How NAC antagonizes SRP and how this is overcome by ER targeting signals are unknown. Here, we found that NAC uses two domains with opposing effects to control SRP access. The core globular domain prevented SRP from binding to signal-less ribosomes, whereas a flexibly attached domain transiently captured SRP to permit scanning of nascent chains. The emergence of an ER-targeting signal destabilized NAC's globular domain and facilitated SRP access to the nascent chain. These findings elucidate how NAC hands over the signal sequence to SRP and imparts specificity of protein localization. Mechanism of signal sequence handover from NAC to SRP on ribosomes during ER-protein targeting.,Jomaa A, Gamerdinger M, Hsieh HH, Wallisch A, Chandrasekaran V, Ulusoy Z, Scaiola A, Hegde RS, Shan SO, Ban N, Deuerling E Science. 2022 Feb 25;375(6583):839-844. doi: 10.1126/science.abl6459. Epub 2022 , Feb 24. PMID:35201867[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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