5A6U

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

Summary for 5A6U

• Entry DOI: 10.2210/pdb5a6u/pdb
• EMDB information: 3068
• Descriptor: SEC61A, SEC61B, SEC61G (3 entities in total)
• Functional Keywords: translation, ribosome, sec61, translocon, endoplasmic reticulum, cryoelectron tomography, subtomogram analysis
• Biological source: CANIS LUPUS FAMILIARIS (DOG); More
• Total number of polymer chains: 3
• Total formula weight: 60333.93

Authors

Pfeffer, S.,Burbaum, L.,Unverdorben, P.,Pech, M.,Chen, Y.,Zimmermann, R.,Beckmann, R.,Foerster, F. (deposition date: 2015-07-01, release date: 2015-10-07, Last modification date: 2024-05-08)

Primary citation

Pfeffer, S.,Burbaum, L.,Unverdorben, P.,Pech, M.,Chen, Y.,Zimmermann, R.,Beckmann, R.,Forster, F.
Structure of the Native Sec61 Protein-Conducting Channel.
Nat.Commun., 6:8403-, 2015

PubMed Abstract: 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-Å 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.

PubMed: 26411746
DOI: 10.1038/NCOMMS9403

Experimental method

ELECTRON MICROSCOPY (9 Å)