title: Alignment of conduits for the nascent polypeptide chain in the ribosome-Sec61 complex.
abstract: An oligomer of the Sec61 trimeric complex is thought to form the protein-conducting channel for protein transport across the endoplasmic reticulum. A purified yeast Sec61 complex bound to monomeric yeast ribosomes as an oligomer in a saturable fashion. Cryo-electron microscopy of the ribosome-Sec61 complex and a three-dimensional reconstruction showed that the Sec61 oligomer is attached to the large ribosomal subunit by a single connection. Moreover, a funnel-shaped pore in the Sec61 oligomer aligned with the exit of a tunnel traversing the large ribosomal subunit, strongly suggesting that both structures function together in the translocation of proteins across the endoplasmic reticulum membrane.
authors.affiliation: Howard Hughes Medical Institute, Laboratory of Cell Biology, Rockefeller University, 1230 York Avenue, New York, NY 10021, USA. beckmar@rockvax.rockefeller.edu
authors.forename: R
authors.initials: R
authors.lastname: Beckmann
authors.forename: D
authors.initials: D
authors.lastname: Bubeck
authors.forename: R
authors.initials: R
authors.lastname: Grassucci
authors.forename: P
authors.initials: P
authors.lastname: Penczek
authors.forename: A
authors.initials: A
authors.lastname: Verschoor
authors.forename: G
authors.initials: G
authors.lastname: Blobel
authors.forename: J
authors.initials: J
authors.lastname: Frank
mesh_terms: D001665:Binding Sites; D001692:Biological Transport; D018870:Endoplasmic Reticulum, Rough / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D007091:Image Processing, Computer-Assisted; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure*; D026901:Membrane Transport Proteins; D008854:Microscopy, Electron; D012270:Ribosomes / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure*; D000069816:SEC Translocation Channels; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D005656:Fungal Proteins; D046911:Macromolecular Substances; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D000069816:SEC Translocation Channels; C499383:SEC61 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins