TY - JOUR
T1 - Cotranslational Stabilization of Sec62/63 within the ER Sec61 Translocon Is Controlled by Distinct Substrate-Driven Translocation Events
AU - Conti, Brian J.
AU - Devaraneni, Prasanna K.
AU - Yang, Zhongying
AU - David, Larry L.
AU - Skach, William
N1 - Funding Information:
We thank R. Zimmermann, R. Gilmore, S. High, and K.E. Matlack for providing antibody reagents. This work was supported by NIH grants GM53457 (W.R.S.), DK51818 (W.R.S.), F32 GM083568 (B.J.C.), and T32 HL083808 (B.J.C.); by NIH core grants P30EY010572 and P30CA069533; by the NIH Shared Instrument Grant S10OD012246; and by the Cystic Fibrosis Foundation Therapeutics grant SKACH05XX0 (W.R.S.).
Publisher Copyright:
© 2015 Elsevier Inc.
PY - 2015/4/16
Y1 - 2015/4/16
N2 - The ER Sec61 translocon is a large macromolecular machine responsible for partitioning secretory and membrane polypeptides into the lumen, cytosol, and lipid bilayer. Because the Sec61 protein-conducting channel has been isolated in multiple membrane-derived complexes, we determined how the nascent polypeptide modulates translocon component associations during defined cotranslational translocation events. The model substrate preprolactin (pPL) was isolated principally with Sec61αβγ upon membrane targeting, whereas higher-order complexes containing OST, TRAP, and TRAM were stabilized following substrate translocation. BlockingpPL translocation by passenger domain folding favored stabilization of an alternate complex that contained Sec61, Sec62, and Sec63. Moreover, Sec62/63 stabilization within the translocon occurred for native endogenous substrates, such as the prion protein, and correlated with a delay in translocationinitiation. These data show that cotranslational translocon contacts are ultimately controlled by the engaged nascent chain and the resultant substrate-driven translocation events.
AB - The ER Sec61 translocon is a large macromolecular machine responsible for partitioning secretory and membrane polypeptides into the lumen, cytosol, and lipid bilayer. Because the Sec61 protein-conducting channel has been isolated in multiple membrane-derived complexes, we determined how the nascent polypeptide modulates translocon component associations during defined cotranslational translocation events. The model substrate preprolactin (pPL) was isolated principally with Sec61αβγ upon membrane targeting, whereas higher-order complexes containing OST, TRAP, and TRAM were stabilized following substrate translocation. BlockingpPL translocation by passenger domain folding favored stabilization of an alternate complex that contained Sec61, Sec62, and Sec63. Moreover, Sec62/63 stabilization within the translocon occurred for native endogenous substrates, such as the prion protein, and correlated with a delay in translocationinitiation. These data show that cotranslational translocon contacts are ultimately controlled by the engaged nascent chain and the resultant substrate-driven translocation events.
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U2 - 10.1016/j.molcel.2015.02.018
DO - 10.1016/j.molcel.2015.02.018
M3 - Article
C2 - 25801167
AN - SCOPUS:84928215514
SN - 1097-2765
VL - 58
SP - 269
EP - 283
JO - Molecular Cell
JF - Molecular Cell
IS - 2
ER -