Protein targeting to endoplasmic reticulum by dilysine signals involves direct retention in addition to retrieval

Andersson, H. and Kappeler, F. and Hauri, H. P.. (1999) Protein targeting to endoplasmic reticulum by dilysine signals involves direct retention in addition to retrieval. Journal of Biological Chemistry, Vol. 274, H. 21. pp. 15080-15084.

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Official URL: http://edoc.unibas.ch/dok/A5257772

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Dilysine signals confer localization of type I membrane proteins to the endoplasmic reticulum (ER). According to the prevailing model these signals target proteins to the ER by COP I-mediated retrieval from post-ER compartments, whereas the actual retention mechanism in the ER is unknown. We expressed chimeric membrane proteins with a C-terminal -Lys-Lys-Ala-Ala (KKAA) or -Lys-Lys-Phe-Phe (KKFF) dilysine signal in Lec-1 cells. Unlike KKFF constructs, which had access to post-ER compartments, the KKAA chimeras were localized to the ER by confocal microscopy and were neither processed by cis-Golgi-specific enzymes in vivo nor included into ER-derived transport vesicles in an in vitro budding assay, suggesting that KKAA-bearing proteins are permanently retained in the ER. The ER localization was nonsaturable and exclusively mediated by the dilysine signal because mutating the lysines to alanines led to cell surface expression of the chimeras. Although the KKAA signal avidly binds COP I in vitro, the ER retention by this signal does not depend on intact COP I in vivo because it was not affected in an epsilon-COP-deficient cell line. We propose that dilysine ER targeting signals can mediate ER retention in addition to retrieval.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Former Organization Units Biozentrum > Pharmacology/Neurobiology (Hauri)
UniBasel Contributors:Hauri, Hans-Peter
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
Last Modified:22 Mar 2012 14:20
Deposited On:22 Mar 2012 13:18

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