Architecture of the Protein-Conducting Channel Associated With the Translating 80S Ribosome

Cell. 2001 Nov 2;107(3):361-72. doi: 10.1016/s0092-8674(01)00541-4.

Abstract

In vitro assembled yeast ribosome-nascent chain complexes (RNCs) containing a signal sequence in the nascent chain were immunopurified and reconstituted with the purified protein-conducting channel (PCC) of yeast endoplasmic reticulum, the Sec61 complex. A cryo-EM reconstruction of the RNC-Sec61 complex at 15.4 A resolution shows a tRNA in the P site. Distinct rRNA elements and proteins of the large ribosomal subunit form four connections with the PCC across a gap of about 10-20 A. Binding of the PCC influences the position of the highly dynamic rRNA expansion segment 27. The RNC-bound Sec61 complex has a compact appearance and was estimated to be a trimer. We propose a binary model of cotranslational translocation entailing only two basic functional states of the translating ribosome-channel complex.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Base Sequence
  • Membrane Proteins / metabolism
  • Molecular Sequence Data
  • Nucleic Acid Conformation
  • Protein Biosynthesis*
  • RNA, Fungal / chemistry
  • RNA, Fungal / metabolism*
  • RNA, Transfer / metabolism*
  • Ribosomal Proteins / metabolism*
  • Ribosomes / metabolism
  • Ribosomes / ultrastructure*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism

Substances

  • Membrane Proteins
  • RNA, Fungal
  • Ribosomal Proteins
  • RNA, Transfer