6n3q

Structural highlights

Function

[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. [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.^[1] [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. [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. [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] [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.

References

1. ↑ Young BP, Craven RA, Reid PJ, Willer M, Stirling CJ. Sec63p and Kar2p are required for the translocation of SRP-dependent precursors into the yeast endoplasmic reticulum in vivo. EMBO J. 2001 Jan 15;20(1-2):262-71. doi: 10.1093/emboj/20.1.262. PMID:11226176 doi:http://dx.doi.org/10.1093/emboj/20.1.262
2. ↑ Itskanov S, Park E. Structure of the posttranslational Sec protein-translocation channel complex from yeast. Science. 2018 Dec 13. pii: science.aav6740. doi: 10.1126/science.aav6740. PMID:30545845 doi:http://dx.doi.org/10.1126/science.aav6740