DOI: 10.1083/jcb.141.4.887. The β Subunit of the Sec61 Complex Facilitates Cotranslational Protein Transport and Interacts with the Signal Peptidase during Translocation

The β Subunit of the Sec61 Complex Facilitates Cotranslational Protein Transport and Interacts with the Signal Peptidase during Translocation

10.1083/jcb.141.4.887

Crossref journal-article

Rockefeller University Press

The Journal of Cell Biology (291)

Abstract

The Sec61 complex is the central component of the protein translocation apparatus of the ER membrane. We have addressed the role of the β subunit (Sec61β) during cotranslational protein translocation. With a reconstituted system, we show that a Sec61 complex lacking Sec61β is essentially inactive when elongation and membrane targeting of a nascent chain occur at the same time. The translocation process is perturbed at a step where the nascent chain would be inserted into the translocation channel. However, if sufficient time is given for the interaction of the nascent polypeptide with the mutant Sec61 complex, translocation is almost normal. Thus Sec61β kinetically facilitates cotranslational translocation, but is not essential for it. Using chemical cross-linking we show that Sec61β not only interacts with subunits of the Sec61 complex but also with the 25-kD subunit of the signal peptidase complex (SPC25), thus demonstrating for the first time a tight interaction between the SPC and the Sec61 complex. Interestingly, the cross-links between Sec61β and SPC25 and between Sec61β and Sec61α depend on the presence of membrane-bound ribosomes, suggesting that these interactions are induced when translocation is initiated. We propose that the SPC is transiently recruited to the translocation site, thus enhancing its activity.

Bibliography

Kalies, K.-U., Rapoport, T. A., & Hartmann, E. (1998). The Î² Subunit of the Sec61 Complex Facilitates Cotranslational Protein Transport and Interacts with the Signal Peptidase during Translocation. The Journal of Cell Biology, 141(4), 887â894.

Authors 3

Kai-Uwe Kalies (first)
Tom A. Rapoport (additional)
Enno Hartmann (additional)

References 21 Referenced 118

10.1126/science.278.5346.2123 / Science / Alignment of conduits for the nascent chain in the ribosome-Sec61 complex by Beckmann (1997)
10.1083/jcb.67.3.835 / J Cell Biol / Transfer of proteins across membranes. I. Presence of proteolytically processed and unprocessed nascent immunoglobulin light chains on membrane-bound ribosomes of murine myeloma by Blobel (1975)
10.1083/jcb.108.2.299 / J Cell Biol / Access of proteinase K to partially translocated nascent polypeptides in intact and detergent-solubilized membranes by Connolly (1989)
10.1016/0092-8674(93)90640-C / Cell / The signal sequence moves through a ribosomal tunnel into a noncytoplasmic aqueous environment at the ER membrane early in translocation by Crowley (1993)
10.1016/0092-8674(94)90424-3 / Cell / Secretory proteins move through the endoplasmic reticulum membrane via an aqueous, gated pore by Crowley (1994)
10.1073/pnas.83.3.581 / Proc Natl Acad Sci USA / Purification of microsomal signal peptidase as a complex by Evans (1986)
10.1074/jbc.271.28.16460 / J Biol Chem / The homologue of mammalian SPC12 is important for efficient signal peptidase activity in Saccharomyces cerevisiae. by Fang (1996)
10.1002/j.1460-2075.1996.tb00492.x / EMBO (Eur Mol Biol Organ) J / A second trimeric complex containing homologs of the Sec61 complex functions in protein transport across the ER membrane of S. cerevisiae. by Finke (1996)
10.1016/0092-8674(93)90483-7 / Cell / Protein translocation into proteoliposomes reconstituted from purified components of the endoplasmic reticulum membrane by Görlich (1993)
10.1038/357047a0 / Nature / A protein of the endoplasmic reticulum involved early in polypeptide translocation by Görlich (1992)
10.1016/0092-8674(92)90517-G / Cell / A mammalian homolog of Sec61p and Secyp is associated with ribosomes and nascent polypeptides during translocation by Görlich (1992)
10.1016/S0092-8674(00)81391-4 / Cell / Oligomeric rings of the Sec61p complex induced by ligands required for protein translocation by Hanein (1996)
10.1016/0092-8674(95)90313-5 / Cell / A posttargeting signal sequence recognition event in the endoplasmic reticulum membrane by Jungnickel (1995)
10.1074/jbc.271.7.3925 / J Biol Chem / Membrane topology of the 12- and the 25-kDa subunit of the mammalian signal peptidase complex by Kalies (1996)
10.1083/jcb.126.4.925 / J Cell Biol / Binding of ribosomes to the rough endoplasmic reticulum mediated by the sec61p-complex by Kalies (1994)
10.1016/S0021-9258(17)44693-X / J Biol Chem / Hen oviduct signal peptidase is an integral membrane protein by Lively (1983)
{'key': '2023072207382661100_B17', 'first-page': '3937', 'article-title': 'Systematic probing of the environment of a translocating secretory protein during translocation through the ER membrane', 'volume': '13', 'author': 'Mothes', 'year': '1994', 'journal-title': 'EMBO (Eur Mol Biol Organ) J'} / EMBO (Eur Mol Biol Organ) J / Systematic probing of the environment of a translocating secretory protein during translocation through the ER membrane by Mothes (1994)
10.1074/jbc.271.46.29094 / J Biol Chem / Structurally related Spc1p and Spc2p of yeast signal peptidase complex are functionally distinct by Mullins (1996)
10.1016/0092-8674(91)90455-8 / Cell / A protein-conducting channel in the endoplasmic reticulum by Simon (1991)
10.1083/jcb.134.1.25 / J Cell Biol / Signal sequence-dependent function of the TRAM protein during early phases of protein transport across the endoplasmic reticulum membrane by Voigt (1996)
10.1016/S0076-6879(83)96010-X / Methods Enzymol / Preparation of microsomal membranes for cotranslational protein translocation by Walter (1983)

Dates

Type	When
Created	23 years, 1 month ago (July 26, 2002, 12:47 p.m.)
Deposited	2 years, 1 month ago (July 22, 2023, 3:39 a.m.)
Indexed	2 weeks, 4 days ago (Aug. 19, 2025, 6:03 a.m.)
Issued	27 years, 3 months ago (May 18, 1998)
Published	27 years, 3 months ago (May 18, 1998)
Published Online	27 years, 3 months ago (May 18, 1998)
Published Print	27 years, 3 months ago (May 18, 1998)

Funders 0

None

BibTeX

@article{Kalies_1998, title={The β Subunit of the Sec61 Complex Facilitates Cotranslational Protein Transport and Interacts with the Signal Peptidase during Translocation}, volume={141}, ISSN={1540-8140}, url={http://dx.doi.org/10.1083/jcb.141.4.887}, DOI={10.1083/jcb.141.4.887}, number={4}, journal={The Journal of Cell Biology}, publisher={Rockefeller University Press}, author={Kalies, Kai-Uwe and Rapoport, Tom A. and Hartmann, Enno}, year={1998}, month=may, pages={887–894} }

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