Structure of Monomeric Yeast and Mammalian Sec61 Complexes Interacting with the Translating Ribosome

• DOI: 10.1126/science.1178535
• Publication Date: 2009-10-30T02:19:34Z
• Authors: Thomas Becker; Shashi Bhushan; Alexander Jarasch; Jean-Paul Armache; Soledad Funes; Fabrice Jossinet; James Gumbart; Thorsten Mielke; Otto Berninghausen; Klaus Schulten; Eric Westhof; Reid Gilmore; Elisabet C. Mandon; Roland Beckmann
• Keywords: Sec61; Cryo-Electron Microscopy; Ribosomal protein; Peptidyl transferase

The trimeric Sec61/SecY complex is a protein-conducting channel (PCC) for secretory and membrane proteins. Although Sec complexes can form oligomers, it has been suggested that single copy may serve as an active PCC. We determined subnanometer-resolution cryo-electron microscopy structures of eukaryotic ribosome-Sec61 complexes. In combination with biochemical data, we found in both idle states, the not oligomeric interacts mainly via two cytoplasmic loops universal ribosomal adaptor site. state, tunnel central pore monomeric PCC were occupied by nascent chain, contacting loop 6 complex. This provides structural basis activity solitary cotranslational protein translocation.