Mutations in the Sec61p channel affecting signal sequence recognition and membrane protein topology

Junne, T. and Schwede, T. and Goder, V. and Spiess, M.. (2007) Mutations in the Sec61p channel affecting signal sequence recognition and membrane protein topology. Journal of biological chemistry, Vol. 282, H. 45. pp. 33201-33209.

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Official URL: http://edoc.unibas.ch/dok/A5259344

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The orientation of most single-spanning membrane proteins obeys the "positive-inside rule", i.e. the flanking region of the transmembrane segment that is more positively charged remains in the cytosol. These membrane proteins are integrated by the Sec61/SecY translocon, but how their orientation is achieved is unknown. We have screened for mutations in yeast Sec61p that alter the orientation of single-spanning membrane proteins. We identified a class of mutants that are less efficient in retaining the positively charged flanking region in the cytosol. Surprisingly, these mutations are located at many different sites in the Sec61/SecY molecule, and they do not only involve charged amino acid residues. All these mutants have a prl phenotype that so far have only been seen in bacteria; they allow proteins with defective signal sequences to be translocated, likely because the Sec61p channel opens more easily. A similar correlation between topology defects and prl phenotype was also seen with previously identified yeast Sec61 mutants. Our results suggest a model in which the regulated opening of the translocon is required for the faithful orientation of membrane proteins.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Former Organization Units Biozentrum > Biochemistry (Spiess)
05 Faculty of Science > Departement Biozentrum > Computational & Systems Biology > Bioinformatics (Schwede)
UniBasel Contributors:Spiess, Martin and Schwede, Torsten
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:American Society of Biological Chemists
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:14 Sep 2012 06:49
Deposited On:22 Mar 2012 13:22

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