6N3Q

Cryo-EM structure of the yeast Sec complex

Summary for 6N3Q

• Entry DOI: 10.2210/pdb6n3q/pdb
• EMDB information: 0336
• Descriptor: Protein transport protein SEC61, Protein transport protein SSS1, Protein transport protein SBH1, ... (6 entities in total)
• Functional Keywords: sec61, sec63, sec71, sec72, sec66, protein translocation, translocon, endoplasmic reticulum, secretion, transport protein
• Biological source: Saccharomyces cerevisiae (strain ATCC 204508 / S288c) (Baker's yeast); More
• Total number of polymer chains: 6
• Total formula weight: 191987.23

Authors

Park, E.,Itskanov, S. (deposition date: 2018-11-16, release date: 2018-12-19, Last modification date: 2024-03-20)

Primary citation

Itskanov, S.,Park, E.
Structure of the posttranslational Sec protein-translocation channel complex from yeast.
Science, 363:84-87, 2019

PubMed Abstract: The Sec61 protein-conducting channel mediates transport of many proteins, such as secretory proteins, across the endoplasmic reticulum (ER) membrane during or after translation. Posttranslational transport is enabled by two additional membrane proteins associated with the channel, Sec63 and Sec62, but its mechanism is poorly understood. We determined a structure of the Sec complex (Sec61-Sec63-Sec71-Sec72) from by cryo-electron microscopy (cryo-EM). The structure shows that Sec63 tightly associates with Sec61 through interactions in cytosolic, transmembrane, and ER-luminal domains, prying open Sec61's lateral gate and translocation pore and thus activating the channel for substrate engagement. Furthermore, Sec63 optimally positions binding sites for cytosolic and luminal chaperones in the complex to enable efficient polypeptide translocation. Our study provides mechanistic insights into eukaryotic posttranslational protein translocation.

PubMed: 30545845
DOI: 10.1126/science.aav6740

Experimental method

ELECTRON MICROSCOPY (3.68 Å)