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First published online 31 October 2006
doi: 10.1242/jcs.03250
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Research Article |
1 Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, 900 South Ashland Avenue, Chicago, IL 60607, USA
2 Banting and Best Department of Medical Research, Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, ON M5S 3E1, Canada
3 Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark
* Author for correspondence (e-mail: sotte{at}uic.edu)
Accepted 7 September 2006
Erv41p and Erv46p are integral membrane proteins conserved across species. They were originally identified as abundant constituents of COPII-coated vesicles, and form a complex which cycles between the endoplasmic reticulum and Golgi complex. Yeast strains lacking these proteins are viable but display subtle secretory phenotypes. In order to obtain information about possible biological roles of this protein complex in endoplasmic reticulum to Golgi transport, we employed the Synthetic Genetic Array approach to screen for synthetic genetic interactions with the erv46 null mutation. We identified synthetic interactions with vma12, vma21, vma22 and vps1 deletion mutations. The vma21
mutation exacerbates transport defects caused by the erv46
mutation. Unexpectedly, yeast strains lacking Vma21p fail to sort the endoplasmic reticulum to Golgi v-SNARE, Bos1p, efficiently into COPII vesicles, yet these vesicles are fully fusion competent. In addition, we set out to identify, by a biochemical approach, proteins interacting with the Erv41p-Erv46p complex. We report a strong interaction between the Erv41p-Erv46p complex and endoplasmic reticulum glucosidase II. Strains lacking a cycling Erv41p-Erv46p complex display a mild glycoprotein processing defect.
Key words: Vesicle trafficking, Endoplasmic reticulum, Golgi, COPII, Erv proteins