Cargo Can Modulate COPII Vesicle Formation from the Endoplasmic Reticulum*
- From the Departments of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, California 92037
Abstract
The COPII coat complex found on endoplasmic reticulum (ER)-derived vesicles plays a critical role in cargo selection. We now address the potential role of biosynthetic cargo in modulating COPII coat assembly and vesicle budding. The ER accumulation of vesicular stomatitis glycoprotein (VSV-G), a transmembrane protein, or the soluble PiZ variant of α1-antitrypsin, reduced levels of general COPII vesicle formation in vivo. Consistent with this result, conditions that prevent the export of VSV-G from the ER led to a significant inhibition of general COPII vesicle budding from ER microsomes and the export of an endogenous recycling protein p58in vitro. In contrast, synchronized export of VSV-G stimulated COPII vesicle budding both in vivo and in vitro. Under conditions where VSV-G is retained in the ER, we find that it can to be recovered in pre-budding complexes containing COPII components. These results suggest that the export of biosynthetic cargo is integrated with ER functions involved in protein folding and oligomerization. The ability of biosynthetic cargo to prevent or enhance ER export suggests that interactions of cargo with the COPII machinery contribute to the formation of vesicles budding from the ER.
Footnotes
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↵* This work was supported in part by Grants GM 42336 and CA 58689 from the National Institutes of Health (to W. E. B).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
This paper is dedicated to the memory of Thomas Kreis.
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↵‡ Recipient of a fellowship grant from the European Molecular Biology Organization and the Human Frontier Sciences Program.
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↵§ Recipient of a Cystic Fibrosis Foundation Post-doctoral fellowship.
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↵¶ Recipient of a fellowship from the Human Frontier Sciences Program and the Muscular Dystrophy Association.
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↵‖ To whom correspondence should be addressed: Dept. of Cell and Molecular Biology, The Scripps Research Institute, 10666 N. Torrey Pines Rd., La Jolla, CA 92037.
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↵2 M. Aridor and W. E. Balch, unpublished observations.
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↵3 S. Bannykh and W. E. Balch, unpublished observations.
- Abbreviations:
- ER
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endoplasmic reticulum
- VSV-G
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vesicular stomatitis glycoprotein
- TGN
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trans-Golgi network
- VSV
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vesicular stomatitis virus
- GST
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glutathioneS-transferase
- NRK
-
normal rat kidney
- OKA
-
okadaic acid
- CHX
-
cycloheximide
- MSP
-
medium speed pellet
- MSS
-
medium speed supernatant
- GTPγS
-
guanosine 5′-3-O-(thio)triphosphate.
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- Received June 17, 1998.
- Revision received November 5, 1998.
- The American Society for Biochemistry and Molecular Biology, Inc.
