The Erv41p–Erv46p complex: multiple export signals are required in trans for COPII‐dependent transport from the ER

• Published in: The EMBO journal Vol. 21; no. 22; pp. 6095 - 6104
• Main Authors: Otte, Stefan, Barlowe, Charles
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 15.11.2002; Blackwell Publishing Ltd; Oxford University Press
• Subjects: Amino Acid Motifs; Amino Acid Sequence; coat proteins; COP-Coated Vesicles - metabolism; Endoplasmic Reticulum, Rough - metabolism; Golgi Apparatus - metabolism; Hydrophobic and Hydrophilic Interactions; Macromolecular Substances; Membrane Proteins - genetics; Membrane Proteins - physiology; Molecular Sequence Data; Mutation; Protein Sorting Signals - physiology; Protein Structure, Tertiary; Protein Transport - physiology; Recombinant Fusion Proteins - metabolism; Saccharomyces cerevisiae - cytology; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - physiology; sorting; Subcellular Fractions - metabolism; trafficking; vesicles
• ISSN: 0261-4189; 1460-2075
• DOI: 10.1093/emboj/cdf598

Erv41p and Erv46p form an integral membrane protein complex that cycles between the endoplasmic reticulum (ER) and Golgi. Both proteins contain a large lumenal domain and short N‐ and C‐terminal tail sequences exposed to the cytosol. The coat protein complex II (COPII) packages the Erv41p–Erv46p complex into ER‐derived vesicles for delivery to the Golgi. We determined signals in the Erv41p–Erv46p complex that are required for COPII‐dependent export from the ER. Mutants lacking the Erv41p or Erv46p C‐terminus accumulated in the ER and were not packaged efficiently into vesicles. We identified an isoleucine–leucine sequence in the Erv41p tail that was required for COPII binding and inclusion of the complex into vesicles. This signal was sufficient for COPII binding but not for ER export. The Erv46p tail contains a phenylalanine–tyrosine sequence required together with the isoleucine–leucine signal in Erv41p for export of the complex. Surprisingly, Erv41p–Erv46p tail‐swapped chimeras were not exported from the ER, indicating that signals in both the Erv41p and the Erv46p tail sequences are required in a specific orientation for efficient packaging of the Erv41p–Erv46p complex.