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Updated: Jul 24, 2026

Applications of pHluorin for Quantitative, Kinetic and High-throughput Analysis of Endocytosis in Budding Yeast
Published on: October 23, 2016
A GTP-binding protein required for secretion rapidly associates with secretory vesicles and the plasma membrane in
B Goud1, A Salminen, N C Walworth
1Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06510.
Abstract:
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.
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