Novel cargo-binding site in the β and δ subunits of coatomer

Kai Michelsen, Volker Schmid, Jutta Metz, Katja Heusser, Urban Liebel, Torsten Schwede, Anne Spang, Blanche Schwappach

    Research output: Contribution to journalArticlepeer-review


    Arginine (R)-based ER localization signals are sorting motifs that confer transient ER localization to unassembled subunits of multimeric membrane proteins. The COPI vesicle coat binds R-based signals but the molecular details remain unknown. Here, we use reporter membrane proteins based on the proteolipid Pmp2 fused to GFP and allele swapping of COPI subunits to map the recognition site for R-based signals. We show that two highly conserved stretches - in the β- and δ-COPI subunits - are required to maintain Pmp2GFP reporters exposing R-based signals in the ER. Combining a deletion of 21 residues in δ-COP together with the mutation of three residues in β-COP gave rise to a COPI coat that had lost its ability to recognize R-based signals, whilst the recognition of C-terminal di-lysine signals remained unimpaired. A homology model of the COPI trunk domain illustrates the recognition of R-based signals by COPI. © The Rockefeller University Press.
    Original languageEnglish
    Pages (from-to)209-217
    Number of pages8
    JournalJournal of Cell Biology
    Issue number2
    Publication statusPublished - 22 Oct 2007


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