Tlg2p, a Yeast Syntaxin Homolog That Resides on the Golgi and Endocytic Structures*
- From the ‡Department of Cell Biology and the§Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06510
Abstract
Intracellular membrane fusion events in eukaryotic cells are thought to be mediated by protein-protein interactions between soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex proteins. We have identified and analyzed a new yeast syntaxin homolog, Tlg2p. Tlg2p is unique among known syntaxin family proteins in possessing a sizeable hydrophilic domain of 63 amino acids that is C-terminal to the membrane spanning region and nonessential for Tlg2p function. Tlg2p resides on the endosome and late Golgi by co-localization with an endocytic intermediate and co-fractionation with markers for both endosomes and late Golgi. Cells depleted for Tlg2p missort a portion of carboxypeptidase Y and are defective in endocytosis. In addition, we report that Tlg2p forms a SEC18-dependent SNARE complex with Snc2p, a vesicle SNARE known to function in Golgi to plasma membrane trafficking. Based on these findings we propose that Tlg2p is a t-SNARE that functions in transport from the endosome to the late Golgi and on the endocytic pathway.
Footnotes
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↵* This work was supported by Program Project Grant CA46128 from the National Cancer Institute (to S. F. N. and P. N.).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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↵¶ Supported by a fellowship from the Human Frontier Science Program.
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↵‖ To whom correspondence should be addressed: Dept. of Cell Biology, Boyer Center for Molecular Medicine, Howard Hughes Medical Inst., 295 Congress Ave., Rm. 254B, New Haven, CT 06510. Tel.: 203-737-5207; Fax: 203-737-5746; E-mail:susan_ferronovick{at}quickmail.yale.edu.
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↵1 The abbreviations used are: SNARE, solubleN-ethylmaleimide-sensitive factor attachment protein receptor; t-SNARE, target SNARE; v-SNARE, vesicle SNARE; NSF,N-ethylmaleimide-sensitive factor; CPY, carboxypeptidase Y; GFP, green fluorescent protein; PCR, polymerase chain reaction; PAGE, polyacrylamide gel electrophoresis; HA, hemagglutinin.
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↵2 E. Grote and P. Novick, unpublished data.
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- Received November 10, 1997.
- Revision received February 23, 1998.
- The American Society for Biochemistry and Molecular Biology, Inc.
