Clathrin‐independent endocytosis contributes to uptake of glucose into BY‐2 protoplasts
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.
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Document Type: Research Article
Affiliations: Institut für Botanik, Technische Universität Darmstadt, Schnittspahnstraße 3–5, D-64287 Darmstadt, Germany
Publication date: May 1, 2012