Tlg2p, a yeast syntaxin homolog that resides on the Golgi and endocytic structures.
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.
Abeliovich
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H
Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06510, USA.
Grote
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Novick
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Ferro-Novick
S
S
D000251:Adenosine Triphosphatases; D000595:Amino Acid Sequence; D002268:Carboxypeptidases / Q000378:metabolism; D043402:Cathepsin A; D002451:Cell Compartmentation; D004705:Endocytosis; D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D006056:Golgi Apparatus / Q000378:metabolism*; D046911:Macromolecular Substances; D008561:Membrane Fusion; D008565:Membrane Proteins / Q000737:chemistry / Q000502:physiology*; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D050765:Qa-SNARE Proteins; D050683:R-SNARE Proteins; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D033921:Vesicular Transport Proteins
D005656:Fungal Proteins; D046911:Macromolecular Substances; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; C081224:PEP12 protein, S cerevisiae; D050765:Qa-SNARE Proteins; D050683:R-SNARE Proteins; D018160:Receptors, Cytoplasmic and Nuclear; C083242:SNC2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C112252:TLG2 protein, S cerevisiae; C107706:VAM3 protein, S cerevisiae; D033921:Vesicular Transport Proteins; D002268:Carboxypeptidases; D043402:Cathepsin A; D000251:Adenosine Triphosphatases; C064404:SEC18 protein, S cerevisiae