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.
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
Cell
Date: Aug. 22, 2003
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