A Human Homolog Can Functionally Replace the Yeast Vesicle-associated SNARE Vti1p in Two Vesicle Transport Pathways*
Abstract
Membrane traffic in eukaryotic cells requires the interaction of a vesicle-associated soluble NSF attachment protein receptor (v-SNARE) on transport vesicles with a SNARE on the target membrane (t-SNARE). Recently, we identified the yeast protein Vti1p as a v-SNARE that is involved in two transport reactions. Vti1p interacts with the prevacuolar t-SNARE Pep12p in Golgi to prevacuolar transport and with the cis-Golgi t-SNARE Sed5p in traffic to the cis-Golgi. Here we describe a human Vti1p homolog, hVti1. Whereas vti1Δcells are inviable, expression of hVti1 allows vti1Δcells to grow at nearly the wild-type growth rate. When expressed in yeast hVti1 can replace Vti1p in both Golgi to prevacuolar transport and in traffic to the cis-Golgi. Sequence comparisons with aSchizosaccharomyces pombe and two different mouse Vti1 homologs led to the identification of a very conserved predicted α-helix. Amino acid exchanges in vti1 mutant alleles defective either in one or both trafficking steps cluster in this domain, suggesting that this structure is probably the binding site for effector proteins.
Footnotes
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↵* This work was supported in part by National Institutes of Health Grant GM32448 (to T. H. S.), the American Heart Association, Oregon Affiliate Grant-In-Aid (to T. H. S.), a Postdoctoral Fellowship (to G. F. v. M), and by the Deutsche Forschungsgemeinschaft (to G. F. v. M.).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵‡ To whom correspondence should be addressed. Tel.: 541-346-5884; Fax: 541-346-4854; E-mail: stevens{at}molbio.uoregon.edu.
- Received August 7, 1997.
- Revision received November 5, 1997.
- The American Society for Biochemistry and Molecular Biology, Inc.
