title: Structure of the mammalian 80S ribosome at 8.7 A resolution.
abstract: In this paper, we present a structure of the mammalian ribosome determined at approximately 8.7 A resolution by electron cryomicroscopy and single-particle methods. A model of the ribosome was created by docking homology models of subunit rRNAs and conserved proteins into the density map. We then modeled expansion segments in the subunit rRNAs and found unclaimed density for approximately 20 proteins. In general, many conserved proteins and novel proteins interact with expansion segments to form an integrated framework that may stabilize the mature ribosome. Our structure provides a snapshot of the mammalian ribosome at the beginning of translation and lends support to current models in which large movements of the small subunit and L1 stalk occur during tRNA translocation. Finally, details are presented for intersubunit bridges that are specific to the eukaryotic ribosome. We suggest that these bridges may help reset the conformation of the ribosome to prepare for the next cycle of chain elongation.
authors.affiliation: Department of Physiology and Biophysics, Boston University School of Medicine, 700 Albany Street, Boston, MA 02118, USA.
authors.forename: Preethi
authors.initials: P
authors.lastname: Chandramouli
authors.forename: Maya
authors.initials: M
authors.lastname: Topf
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Ménétret
authors.forename: Narayanan
authors.initials: N
authors.lastname: Eswar
authors.forename: Jamie J
authors.initials: JJ
authors.lastname: Cannone
authors.forename: Robin R
authors.initials: RR
authors.lastname: Gutell
authors.forename: Andrej
authors.initials: A
authors.lastname: Sali
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Akey
mesh_terms: D000818:Animals; D020285:Cryoelectron Microscopy; D004285:Dogs; D007091:Image Processing, Computer-Assisted; D008958:Models, Molecular; D014176:Protein Biosynthesis; D012335:RNA, Ribosomal / Q000737:chemistry*; D012343:RNA, Transfer / Q000737:chemistry; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface / Q000737:chemistry; D012269:Ribosomal Proteins / Q000737:chemistry*; D054682:Ribosome Subunits, Small, Eukaryotic / Q000737:chemistry*; D012270:Ribosomes / Q000737:chemistry*
chemical_list: D012335:RNA, Ribosomal; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface; D012269:Ribosomal Proteins; D012343:RNA, Transfer