CHARACTERIZATION OF GLUCOSE-TRANSPORT SYSTEM IN DROSOPHILA KC CELLS

We have characterized the glucose transport system in the Kc cells of Drosophila melanogaster. The transporter is stereospecific and can be inhibited by both cytochalasin B and phloretin, with k(i) values of 4 muM and 30 muM for cytochalasin B and phloretin. respectively. Moreover, phloridzin does not affect uptake of glucose by Kc cells. Thus, on the basis of inhibitor studies, it appears that this insect cell line contains glucose transporters similar to those of the mammalian cells. However. probes prepared from rat transporter cDNAs showed no cross-hybridization with Drosophila RNA under moderately stringent conditions. Sugar selectivity has also been investigated by competition assay. The k(m) values for D-glucose, 2-deoXy-D-glucose, D-fructose and D-galactose are 2 mM, 6 mM, 17 mM and 16 mM, respectively. The results indicate that this transporter prefers D-glucose and that it does not discriminate between D-galactose and D-fructose.