TY - JOUR T1 - Modular assembly of the nucleolar large subunit processome JF - bioRxiv DO - 10.1101/223412 SP - 223412 AU - Zahra Assur Sanghai AU - Linamarie Miller AU - Kelly R. Molloy AU - Jonas Barandun AU - Mirjam Hunziker AU - Malik Chaker-Margot AU - Junjie Wang AU - Brian T. Chait AU - Sebastian Klinge Y1 - 2017/01/01 UR - http://biorxiv.org/content/early/2017/11/21/223412.abstract N2 - Early co-transcriptional events of eukaryotic ribosome assembly result in the formation of the small and large subunit processomes. We have determined cryo-EM reconstructions of the nucleolar large subunit processome in different conformational states at resolutions up to 3.4 Ã…ngstroms. These structures reveal how steric hindrance and molecular mimicry are used to prevent premature folding states and binding of later factors. This is accomplished by the concerted activity of 21 ribosome assembly factors that stabilize and remodel pre-ribosomal RNA and ribosomal proteins. Mutually exclusive conformations of these particles suggest that the formation of the polypeptide exit tunnel is achieved through different folding pathways during subsequent stages of ribosome assembly. ER -