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| <SX load='6n3q' size='340' side='right' viewer='molstar' caption='[[6n3q]], [[Resolution|resolution]] 3.68Å' scene=''> | | <SX load='6n3q' size='340' side='right' viewer='molstar' caption='[[6n3q]], [[Resolution|resolution]] 3.68Å' scene=''> |
| == Structural highlights == | | == Structural highlights == |
- | <table><tr><td colspan='2'>[[6n3q]] is a 6 chain structure with sequence from [http://en.wikipedia.org/wiki/Baker's_yeast Baker's yeast]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6N3Q OCA]. For a <b>guided tour on the structure components</b> use [http://proteopedia.org/fgij/fg.htm?mol=6N3Q FirstGlance]. <br> | + | <table><tr><td colspan='2'>[[6n3q]] is a 6 chain structure with sequence from [https://en.wikipedia.org/wiki/Saccharomyces_cerevisiae_S288C Saccharomyces cerevisiae S288C]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6N3Q OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6N3Q FirstGlance]. <br> |
- | </td></tr><tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://proteopedia.org/fgij/fg.htm?mol=6n3q FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6n3q OCA], [http://pdbe.org/6n3q PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=6n3q RCSB], [http://www.ebi.ac.uk/pdbsum/6n3q PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=6n3q ProSAT]</span></td></tr> | + | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Electron Microscopy, [[Resolution|Resolution]] 3.68Å</td></tr> |
| + | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=6n3q FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6n3q OCA], [https://pdbe.org/6n3q PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6n3q RCSB], [https://www.ebi.ac.uk/pdbsum/6n3q PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6n3q ProSAT]</span></td></tr> |
| </table> | | </table> |
| == Function == | | == Function == |
- | [[http://www.uniprot.org/uniprot/SEC72_YEAST SEC72_YEAST]] Acts as non-essential component of the Sec62/63 complex which is involved in SRP-independent post-translational translocation across the endoplasmic reticulum (ER) and functions together with the Sec61 complex and KAR2 in a channel-forming translocon complex. A cycle of assembly and disassembly of Sec62/63 complex from SEC61 may govern the activity of the translocon. SEC72 may be involved in signal peptide recognition for a defined subset of leader peptides, or may increase the efficiency of unusual or "difficult" secretory precursors to the translocation pore, it may be that this protein binds charged leader peptides to the membrane until they engage the translocation apparatus. [[http://www.uniprot.org/uniprot/SEC63_YEAST SEC63_YEAST]] Acts as component of the Sec62/63 complex which is involved in SRP-independent post-translational translocation across the endoplasmic reticulum (ER) and functions together with the Sec61 complex and KAR2 in a channel-forming translocon complex. A cycle of assembly and disassembly of Sec62/63 complex from SEC61 may govern the activity of the translocon. SEC63 may affect SEC1-polypeptide interactions by increasing the affinity of targeting pathways for SEC61 and/or by modifying SEC61 to allow more efficient polypeptide interaction. May also be involved in SRP-dependent cotranslational translocation. Is essential for cell growth and for germination.<ref>PMID:11226176</ref> [[http://www.uniprot.org/uniprot/SC61A_YEAST SC61A_YEAST]] Part of the Sec61 complex, which is the major component of a channel-forming translocon complex that mediates protein translocation across the endoplasmic reticulum (ER). The functional states of the translocon complex include co- and post-translational ER import, cotranslational membrane protein integration and retrograde transport of misfolded proteins out of the ER. In the cotranslational pathway, ribosomes synthesizing presecretory proteins are targeted to the translocon by the cytosolic signal recognition particle (SRP) and its ER-localized receptor. The association of the Sec61 complex with the ribosome is mediated by the 28S rRNA of the large ribosomal subunit. SRP-independent post-translational translocation requires the association of additional factors, such as the Sec62/63 complex and KAR2. In an initial step, the signal sequence seems to bind simultaneously to SEC61 and SEC62. A cycle of assembly and disassembly of Sec62/63 complex from SEC61 may govern the activity of the translocon. SEC61 mediates the association with the ribosome. [[http://www.uniprot.org/uniprot/SC6B1_YEAST SC6B1_YEAST]] Part of the Sec61 complex, which is the major component of a channel-forming translocon complex that mediates protein translocation across the endoplasmic reticulum (ER). The functional states of the translocon complex include co- and post-translational ER import, cotranslational membrane protein integration and retrograde transport of misfolded proteins out of the ER. In the cotranslational pathway, ribosomes synthesizing presecretory proteins are targeted to the translocon by the cytosolic signal recognition particle (SRP) and its ER-localized receptor. The association of the Sec61 complex with the ribosome is mediated by the 28S rRNA of the large ribosomal subunit. SRP-independent post-translational translocation requires the association of additional factors, such as the Sec62/63 complex and KAR2. [[http://www.uniprot.org/uniprot/SC61G_YEAST SC61G_YEAST]] Part of the Sec61 complex, which is the major component of channel-forming translocon complex that mediates protein translocation across the endoplasmic reticulum (ER). The functional states of the translocon complex include co- and post-translational ER import, cotranslational membrane protein integration and retrograde transport of misfolded proteins out of the ER. In the cotranslational pathway, ribosomes synthesizing presecretory proteins are targeted to the translocon by the cytosolic signal recognition particle (SRP) and its ER-localized receptor. The association of the Sec61 complex with the ribosome is mediated by the 28S rRNA of the large ribosomal subunit. SRP-independent post-translational translocation requires the association of additional factors, such as the Sec62/63 complex and KAR2. Also part of the Ssh1 complex, which probably is the major component of a channel-forming translocon complex that may function exclusively in the cotranslational pathway of protein ER import.[HAMAP-Rule:MF_00422] [[http://www.uniprot.org/uniprot/SEC66_YEAST SEC66_YEAST]] Acts as component of the Sec62/63 complex which is involved in SRP-independent post-translational translocation across the endoplasmic reticulum (ER) and functions together with the Sec61 complex and KAR2 in a channel-forming translocon complex. A cycle of assembly and disassembly of Sec62/63 complex from SEC61 may govern the activity of the translocon. SEC66 is required to attach or retain SEC72 in the SEC63 complex. It is essential for growth at elevated temperatures. | + | [https://www.uniprot.org/uniprot/SC61A_YEAST SC61A_YEAST] Part of the Sec61 complex, which is the major component of a channel-forming translocon complex that mediates protein translocation across the endoplasmic reticulum (ER). The functional states of the translocon complex include co- and post-translational ER import, cotranslational membrane protein integration and retrograde transport of misfolded proteins out of the ER. In the cotranslational pathway, ribosomes synthesizing presecretory proteins are targeted to the translocon by the cytosolic signal recognition particle (SRP) and its ER-localized receptor. The association of the Sec61 complex with the ribosome is mediated by the 28S rRNA of the large ribosomal subunit. SRP-independent post-translational translocation requires the association of additional factors, such as the Sec62/63 complex and KAR2. In an initial step, the signal sequence seems to bind simultaneously to SEC61 and SEC62. A cycle of assembly and disassembly of Sec62/63 complex from SEC61 may govern the activity of the translocon. SEC61 mediates the association with the ribosome. |
- | <div style="background-color:#fffaf0;">
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- | == Publication Abstract from PubMed ==
| + | |
- | The Sec61 protein-conducting channel mediates transport of many proteins, such as secretory proteins, across the endoplasmic reticulum (ER) membrane during or after translation. Posttranslational transport is enabled by two additional membrane proteins associated with the channel, Sec63 and Sec62, but its mechanism is poorly understood. We determined a structure of the Sec complex (Sec61-Sec63-Sec71-Sec72) from Saccharomyces cerevisiae by cryo-electron microscopy (cryo-EM). The structure shows that Sec63 tightly associates with Sec61 though interactions in cytosolic, transmembrane, and ER-luminal domains, prying open Sec61's lateral gate and translocation pore and thus activating the channel for substrate engagement. Furthermore, Sec63 optimally positions binding sites for cytosolic and luminal chaperones in the complex to enable efficient polypeptide translocation. Our study provides mechanistic insights into eukaryotic posttranslational protein translocation.
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- | Structure of the posttranslational Sec protein-translocation channel complex from yeast.,Itskanov S, Park E Science. 2018 Dec 13. pii: science.aav6740. doi: 10.1126/science.aav6740. PMID:30545845<ref>PMID:30545845</ref>
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- | From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br>
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- | </div>
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- | <div class="pdbe-citations 6n3q" style="background-color:#fffaf0;"></div>
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- | == References ==
| + | |
- | <references/>
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| __TOC__ | | __TOC__ |
| </SX> | | </SX> |
- | [[Category: Baker's yeast]] | |
| [[Category: Large Structures]] | | [[Category: Large Structures]] |
- | [[Category: Itskanov, S]] | + | [[Category: Saccharomyces cerevisiae S288C]] |
- | [[Category: Park, E]] | + | [[Category: Itskanov S]] |
- | [[Category: Endoplasmic reticulum]] | + | [[Category: Park E]] |
- | [[Category: Protein translocation]]
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- | [[Category: Sec61]]
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- | [[Category: Sec63]]
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- | [[Category: Sec66]]
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- | [[Category: Sec71]]
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- | [[Category: Sec72]]
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- | [[Category: Secretion]]
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- | [[Category: Translocon]]
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- | [[Category: Transport protein]]
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