Exocytosis and Endocytosis of Small Vesicles across the Plasma Membrane in Saccharomyces cerevisiae

Membranes

Kathryn Stein¹ 

[1] Department of Cellular and Molecular Physiology, Penn State College of Medicine, 500 University Drive, Hershey, PA 17033, USA; E-Mail

关键词: fructose-1;    6-bisphosphatase;    phosphoenolpyruvate carboxykinase;    isocitrate lyase;    malate dehydrogenase;    glyceraldehyde-3-phosphate dehydrogenase;    cyclophilin A;    vacuole import and degradation;    extracellular vesicles;    exosomes;   

DOI  :  10.3390/membranes4030608

来源: mdpi

【 摘 要 】

When Saccharomyces cerevisiae is starved of glucose, the gluconeogenic enzymes fructose-1,6-bisphosphatase (FBPase), phosphoenolpyruvate carboxykinase, isocitrate lyase, and malate dehydrogenase, as well as the non-gluconeogenic enzymes glyceraldehyde-3-phosphate dehydrogenase and cyclophilin A, are secreted into the periplasm. In the extracellular fraction, these secreted proteins are associated with small vesicles that account for more than 90% of the total number of extracellular structures observed. When glucose is added to glucose-starved cells, FBPase is internalized and associated with clusters of small vesicles in the cytoplasm. Specifically, the internalization of FBPase results in the decline of FBPase and vesicles in the extracellular fraction and their appearance in the cytoplasm. The clearance of extracellular vesicles and vesicle-associated proteins from the extracellular fraction is dependent on the endocytosis gene END3. This internalization is regulated when cells are transferred from low to high glucose. It is rapidly occurring and is a high capacity process, as clusters of vesicles occupy 10%–20% of the total volume in the cytoplasm in glucose re-fed cells. FBPase internalization also requires the VPS34 gene encoding PI3K. Following internalization, FBPase is delivered to the vacuole for degradation, whereas proteins that are not degraded may be recycled.

【 授权许可】

CC BY   
© 2014 by the authors; licensee MDPI, Basel, Switzerland.