Sec61p contributes to signal sequence orientation according to the positive-inside rule

Goder, V. and Junne, T. and Spiess, M.. (2004) Sec61p contributes to signal sequence orientation according to the positive-inside rule. Molecular Biology of the Cell, 15 (3). pp. 1470-1478.

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Official URL: http://edoc.unibas.ch/dok/A5258047

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Protein targeting to the endoplasmic reticulum is mediated by signal or signal-anchor sequences. They also play an important role in protein topogenesis, because their orientation in the translocon determines whether their N- or C-terminal sequence is translocated. Signal orientation is primarily determined by charged residues flanking the hydrophobic core, whereby the more positive end is predominantly positioned to the cytoplasmic side of the membrane, a phenomenon known as the "positive-inside rule." We tested the role of conserved charged residues of Sec61p, the major component of the translocon in Saccharomyces cerevisiae, in orienting signals according to their flanking charges by site-directed mutagenesis by using diagnostic model proteins. Mutation of R67, R74, or E382 in Sec61p reduced C-terminal translocation of a signal-anchor protein with a positive N-terminal flanking sequence and increased it for signal-anchor proteins with positive C-terminal sequences. These mutations produced a stronger effect on substrates with greater charge difference across the hydrophobic core of the signal. For some of the substrates, a charge mutation in Sec61p had a similar effect as one in the substrate polypeptides. Although these three residues do not account for the entire charge effect in signal orientation, the results show that Sec61p contributes to the positive-inside rule.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Former Organization Units Biozentrum > Biochemistry (Spiess)
UniBasel Contributors:Spiess, Martin
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:American Society for Cell Biology
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:07 Nov 2017 10:57
Deposited On:22 Mar 2012 13:19

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