4v7e

Model of the small subunit RNA based on a 5.5 A cryo-EM map of Triticum aestivum translating 80S ribosome

spinqualitylabelsall models 4v7e, resolution 5.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4v7e is a 88 chain structure with sequence from Triticum aestivum. This structure supersedes and combines the now removed PDB entries 3j5z, 3j60, 3j61 and 3j62. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. NonStd Res: UNK Resources: FirstGlance, OCA, RCSB, PDBsum Warning: this is a large structure, and loading might take a long time or not happen at all. Publication Abstract from PubMed The biogenesis of secretory as well as transmembrane proteins requires the activity of the universally conserved protein-conducting channel (PCC), the Sec61 complex (SecY complex in bacteria). In eukaryotic cells the PCC is located in the membrane of the endoplasmic reticulum where it can bind to translating ribosomes for co-translational protein transport. The Sec complex consists of three subunits (Sec61alpha, beta and gamma) and provides an aqueous environment for the translocation of hydrophilic peptides as well as a lateral opening in the Sec61alpha subunit that has been proposed to act as a gate for the membrane partitioning of hydrophobic domains. A plug helix and a so-called pore ring are believed to seal the PCC against ion flow and are proposed to rearrange for accommodation of translocating peptides. Several crystal and cryo-electron microscopy structures revealed different conformations of closed and partially open Sec61 and SecY complexes. However, in none of these samples has the translocation state been unambiguously defined biochemically. Here we present cryo-electron microscopy structures of ribosome-bound Sec61 complexes engaged in translocation or membrane insertion of nascent peptides. Our data show that a hydrophilic peptide can translocate through the Sec complex with an essentially closed lateral gate and an only slightly rearranged central channel. Membrane insertion of a hydrophobic domain seems to occur with the Sec complex opening the proposed lateral gate while rearranging the plug to maintain an ion permeability barrier. Taken together, we provide a structural model for the basic activities of the Sec61 complex as a protein-conducting channel. Structures of the Sec61 complex engaged in nascent peptide translocation or membrane insertion.,Gogala M, Becker T, Beatrix B, Armache JP, Barrio-Garcia C, Berninghausen O, Beckmann R Nature. 2014 Feb 6;506(7486):107-10. doi: 10.1038/nature12950. PMID:24499919 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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