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Updated: May 12, 2026

Using SecM Arrest Sequence as a Tool to Isolate Ribosome Bound Polypeptides
Published on: June 19, 2012
Oligomeric rings of the Sec61p complex induced by ligands required for protein translocation
D Hanein1, K E Matlack, B Jungnickel
1Department of Biophysics, Boston University School of Medicine, Massachusetts 02218-2394, USA.
Abstract:
The heterotrimeric Sec61p complex is a major component of the protein-conducting channel of the endoplasmic reticulum (ER) membrane, associating with either ribosomes or the Sec62/63 complex to perform co- and posttranslational transport, respectively. We show by electron microscopy that purified mammalian and yeast Sec61p complexes in detergent form cylindrical oligomers with a diameter of approximately 85 A and a central pore of approximately 20 A. Each oligomer contains 3-4 heterotrimers. Similar ring structures are seen in reconstituted proteoliposomes and native membranes. Oligomer formation by the reconstituted Sec61p complex is stimulated by its association with ribosomes or the Sec62/63p complex. We propose that these cylindrical oligomers represent protein-conducting channels of the ER, formed by ligands specific for co- and posttranslational transport.
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