Figure 6.

GLUT2 lysosomal degradation is secretogogue dependent. Min6B1 cells were plated in six-well plates and transfected with 2 μg Myc-GLUT2 construct per well. A, The cells were cultured in 5 mm glucose for 24 h, and the surface myc-GLUT2 was labeled at 4 C with or without 50 μm chloroquine. The cells were then warmed to 37 C in culture medium containing either 5 or 25 mm glucose in the presence and absence of 50 μm chloroquine. B, The Myc-GLUT2 transfected cells were cultured in 5 mm glucose for 24 h, and the surface myc-GLUT2 was labeled at 4 C with or without 50 μm chloroquine. The cells were then warmed to 37 C in culture medium containing either 5 mm glucose or 20 mm arginine in the presence and absence of 50 μm chloroquine. Endocytosis was quantified by dividing the plasma membrane surface Texas Red fluorescent intensity by the total cell content of Texas Red fluorescent intensity in 10 cells for each time point per experiment using confocal fluorescence microscopy. The mean value was calculated from the average of three independent experiments.