A GTP-binding protein required for secretion rapidly associates with secretory vesicles and the plasma membrane in yeast

Cell. 1988 Jun 3;53(5):753-68. doi: 10.1016/0092-8674(88)90093-1.


SEC4, one of the 10 genes involved in the final stage of the yeast secretory pathway, encodes a ras-like, GTP-binding protein. In wild-type cells, Sec4 protein is located on the cytoplasmic face of both the plasma membrane and the secretory vesicles in transit to the cell surface. In all post-Golgi blocked sec mutants, Sec4p is predominantly associated with the secretory vesicles that accumulate as a result of the secretory block. Sec4p is synthesized as a soluble protein that rapidly (t1/2 less than or equal to 1 min) and tightly associates with secretory vesicles and the plasma membrane by virtue of a conformational change of a covalent modification. These data suggest that Sec4p may function as a "G" protein on the vesicle surface to transduce an intracellular signal needed to regulate transport between the Golgi apparatus and the plasma membrane.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Cell Membrane / metabolism
  • Cytoplasmic Granules / metabolism*
  • Fluorescent Antibody Technique
  • GTP-Binding Proteins / genetics
  • GTP-Binding Proteins / metabolism*
  • Genes
  • Genes, Fungal
  • Genotype
  • Kinetics
  • Mutation
  • Plasmids
  • Promoter Regions, Genetic
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism*


  • GTP-Binding Proteins