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SNARE selectivity of the COPII coat.

The COPII coat buds transport vesicles from the endoplasmic reticulum that incorporate cargo and SNARE molecules. Here, we show that recognition of the ER-Golgi SNAREs Bet1, Sed5, and Sec22 occurs through three binding sites on the Sec23/24 subcomplex of yeast COPII. The A site binds to the YNNSNPF motif of Sed5. The B site binds to Lxx-L/M-E sequences present in both the Bet1 and Sed5 molecules, as well as to the DxE cargo-sorting signal. A third, spatially distinct site binds to Sec22. COPII selects the free v-SNARE form of Bet1 because the LxxLE sequence is sequestered in the four-helix bundle of the v-/t-SNARE complex. COPII favors Sed5 within the Sed5/Bos1/Sec22 t-SNARE complex because t-SNARE assembly removes autoinhibitory contacts to expose the YNNSNPF motif. The COPII coat seems to be a specific conductor of the fusogenic forms of these SNAREs, suggesting how vesicle fusion specificity may be programmed during budding.

Pubmed ID: 12941276


  • Mossessova E
  • Bickford LC
  • Goldberg J



Publication Data

August 22, 2003

Associated Grants


Mesh Terms

  • Amino Acid Motifs
  • COP-Coated Vesicles
  • Carrier Proteins
  • Crystallography, X-Ray
  • GTPase-Activating Proteins
  • Macromolecular Substances
  • Membrane Proteins
  • Membrane Transport Proteins
  • Models, Molecular
  • Phosphoproteins
  • Protein Binding
  • Protein Structure, Tertiary
  • Protein Transport
  • Qa-SNARE Proteins
  • Qc-SNARE Proteins
  • R-SNARE Proteins
  • Receptors, Cell Surface
  • SNARE Proteins
  • Saccharomyces cerevisiae Proteins
  • Substrate Specificity
  • Vesicular Transport Proteins