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-Structure paper
タイトル | Structure of the native Sec61 protein-conducting channel. |
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ジャーナル・号・ページ | Nat Commun, Vol. 6, Page 8403, Year 2015 |
掲載日 | 2015年9月28日 |
著者 | Stefan Pfeffer / Laura Burbaum / Pia Unverdorben / Markus Pech / Yuxiang Chen / Richard Zimmermann / Roland Beckmann / Friedrich Förster / |
PubMed 要旨 | In mammalian cells, secretory and membrane proteins are translocated across or inserted into the endoplasmic reticulum (ER) membrane by the universally conserved protein-conducting channel Sec61, ...In mammalian cells, secretory and membrane proteins are translocated across or inserted into the endoplasmic reticulum (ER) membrane by the universally conserved protein-conducting channel Sec61, which has been structurally studied in isolated, detergent-solubilized states. Here we structurally and functionally characterize native, non-solubilized ribosome-Sec61 complexes on rough ER vesicles using cryo-electron tomography and ribosome profiling. Surprisingly, the 9-Å resolution subtomogram average reveals Sec61 in a laterally open conformation, even though the channel is not in the process of inserting membrane proteins into the lipid bilayer. In contrast to recent mechanistic models for polypeptide translocation and insertion, our results indicate that the laterally open conformation of Sec61 is the only conformation present in the ribosome-bound translocon complex, independent of its functional state. Consistent with earlier functional studies, our structure suggests that the ribosome alone, even without a nascent chain, is sufficient for lateral opening of Sec61 in a lipid environment. |
リンク | Nat Commun / PubMed:26411746 / PubMed Central |
手法 | EM (サブトモグラム平均) / EM (トモグラフィー) |
解像度 | 9.0 - 10.0 Å |
構造データ | EMDB-3068: Mammalian ribosome bound to the native Sec61 protein-conducting channel in the 'non-inserting' state ('conventional' alignment) EMDB-3069: EMDB-3070: EMDB-3071: EMDB-3072: |
由来 |
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キーワード | TRANSLATION / RIBOSOME / SEC61 / TRANSLOCON / ENDOPLASMIC RETICULUM / CRYOELECTRON TOMOGRAPHY / SUBTOMOGRAM ANALYSIS |