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Updated: May 11, 2026

Production of Disulfide-stabilized Transmembrane Peptide Complexes for Structural Studies
Published on: March 6, 2013
Architecture of the protein-conducting channel associated with the translating 80S ribosome
R Beckmann1, C M Spahn, N Eswar
1Laboratory of Cell Biology, Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA. roland.beckmann@charite.de
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.
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In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the translocon complex.

