5a6u | pdb_00005a6u

Native mammalian ribosome-bound Sec61 protein-conducting channel in the 'non-inserting' state

Loading... Status: waiting for Mol* initialization Structural highlights 5a6u is a 3 chain structure with sequence from Canis lupus familiaris. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 9Å Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function S61A1_CANLF Publication Abstract from PubMed In mammalian cells, secretory and membrane proteins are translocated across or inserted into the endoplasmic reticulum (ER) membrane by the universally conserved protein-conducting channel Sec61, which has been structurally studied in isolated, detergent-solubilized states. Here we structurally and functionally characterize native, non-solubilized ribosome-Sec61 complexes on rough ER vesicles using cryo-electron tomography and ribosome profiling. Surprisingly, the 9-A resolution subtomogram average reveals Sec61 in a laterally open conformation, even though the channel is not in the process of inserting membrane proteins into the lipid bilayer. In contrast to recent mechanistic models for polypeptide translocation and insertion, our results indicate that the laterally open conformation of Sec61 is the only conformation present in the ribosome-bound translocon complex, independent of its functional state. Consistent with earlier functional studies, our structure suggests that the ribosome alone, even without a nascent chain, is sufficient for lateral opening of Sec61 in a lipid environment. Structure of the native Sec61 protein-conducting channel.,Pfeffer S, Burbaum L, Unverdorben P, Pech M, Chen Y, Zimmermann R, Beckmann R, Forster F Nat Commun. 2015 Sep 28;6:8403. doi: 10.1038/ncomms9403. PMID:26411746 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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