A novel SNARE complex implicated in vesicle fusion with the endoplasmic reticulum.

Intracellular vesicular traffic is controlled in part by v- and t-SNAREs, integral membrane proteins which allow specific interaction and fusion between vesicles (v-SNAREs) and their target membranes (t-SNAREs). In yeast, retrograde transport from the Golgi complex to the ER is mediated by the ER t-SNARE Ufe1p, and also requires two ...
other ER proteins, Sec20p and Tip20p, which bind each other. Although Sec20p is not a typical SNARE, we show that both it and Tip20p can be co-precipitated with Ufe1p, and that a growth-inhibiting mutation in Ufe1p can be compensated by a mutation in Sec20p. Furthermore, Sec22p, a v-SNARE implicated in forward transport from ER to Golgi, co-precipitates with Ufe1p and Sec20p, and SEC22 acts as an allele-specific multicopy suppressor of a temperature-sensitive ufe1 mutation. These results define a new functional SNARE complex, with features distinct from the plasma membrane and cis-Golgi complexes previously identified. They also show that a single v-SNARE can be involved in both anterograde and retrograde transport, which suggests that the mere presence of a particular v-SNARE may not be sufficient to determine the preferred target for a transport vesicle.
Mesh Terms:
Amino Acid Sequence, Carrier Proteins, Cell Compartmentation, Endoplasmic Reticulum, Fungal Proteins, Gene Dosage, Glycoproteins, HSP70 Heat-Shock Proteins, Macromolecular Substances, Membrane Fusion, Membrane Glycoproteins, Membrane Proteins, Molecular Sequence Data, Mutation, Precipitin Tests, Protein Binding, Qa-SNARE Proteins, Qb-SNARE Proteins, R-SNARE Proteins, Receptors, Cell Surface, Saccharomyces cerevisiae Proteins, Suppression, Genetic, Vesicular Transport Proteins, Yeasts
EMBO J.
Date: Jun. 02, 1997
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