2-(n-(7-nitrobenz-2-oxa-1-3-diazol-4-yl)amino)-2-deoxyglucose and ikarugamycin

In eukaryotic cells, several pathways exist for the internalization of plasma membrane proteins and extracellular cargo molecules. These endocytic pathways can be divided into clathrin-dependent and clathrin-independent pathways. While clathrin-dependent pathways are known to be involved in a variety of cellular processes in plants, clathrin-independent pathways have so far only been identified in animal and yeast cells. Here we show that internalization of fluorescent glucose into BY-2 cells leads to accumulation of the sugar in compartments of the endocytic pathway. This endocytic uptake of glucose was not blocked by ikarugamycin, an inhibitor of clathrin-dependent endocytosis, suggesting a role for clathrin-independent endocytosis in glucose uptake. Investigations of fusion and fission of single vesicles by membrane capacitance measurements revealed stimulation of endocytic activity by extracellular glucose. Glucose-stimulated fission of vesicles was not affected by addition of ikarugamycin or blocking of clathrin coat formation by transient over-expression of HUB1 (the C-terminal part of the clathrin heavy chain). These data demonstrate that clathrin-independent endocytosis does occur in plant cells. This pathway may represent a common mechanism for the uptake of external nutrients.

Topics: 4-Chloro-7-nitrobenzofurazan; Biological Transport; Cell Line; Clathrin Heavy Chains; Clathrin-Coated Vesicles; Cytoplasmic Vesicles; Cytosol; Deoxyglucose; Endocytosis; Endosomes; Glucose; Green Fluorescent Proteins; Lactams; Microscopy, Confocal; Nicotiana; Protoplasts; Transfection; Vacuoles