Yeast exocytic v-SNAREs confer endocytosis

Mol Biol Cell. 2000 Oct;11(10):3629-43. doi: 10.1091/mbc.11.10.3629.

Abstract

In yeast, homologues of the synaptobrevin/VAMP family of v-SNAREs (Snc1 and Snc2) confer the docking and fusion of secretory vesicles at the cell surface. As no v-SNARE has been shown to confer endocytosis, we examined whether yeast lacking the SNC genes, or possessing a temperature-sensitive allele of SNC1 (SNC1(ala43)), are deficient in the endocytic uptake of components from the cell surface. We found that both SNC and temperature-shifted SNC1(ala43) yeast are deficient in their ability to deliver the soluble dye FM4-64 to the vacuole. Under conditions in which vesicles accumulate, FM4-64 stained primarily the cytoplasm as well as fragmented vacuoles. In addition, alpha-factor-stimulated endocytosis of the alpha-factor receptor, Ste2, was fully blocked, as evidenced using a Ste2-green fluorescent protein fusion protein as well as metabolic labeling studies. This suggests a direct role for Snc v-SNAREs in the retrieval of membrane proteins from the cell surface. Moreover, this idea is supported by genetic and physical data that demonstrate functional interactions with t-SNAREs that confer endosomal transport (e.g., Tlg1,2). Notably, Snc1(ala43) was found to be nonfunctional in cells lacking Tlg1 or Tlg2. Thus, we propose that synaptobrevin/VAMP family members are engaged in anterograde and retrograde protein sorting steps between the Golgi and the plasma membrane.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Cloning, Molecular
  • Endocytosis / genetics
  • Endocytosis / physiology*
  • Exocytosis / physiology*
  • Fungal Proteins / genetics
  • Fungal Proteins / physiology*
  • Genotype
  • Mating Factor
  • Membrane Proteins*
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Oligodeoxyribonucleotides
  • Peptides / physiology
  • R-SNARE Proteins
  • Recombinant Proteins / metabolism
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / physiology*
  • Saccharomyces cerevisiae Proteins*
  • Temperature
  • Vacuoles / physiology*

Substances

  • Fungal Proteins
  • Membrane Proteins
  • Oligodeoxyribonucleotides
  • Peptides
  • R-SNARE Proteins
  • Recombinant Proteins
  • SNC1 protein, S cerevisiae
  • SNC2 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Mating Factor