Figure 10.

Partial association of GLUT4 and transferrin receptor-containing structures at the surface and in the core of basal fibers. Single basal fibers were stained simultaneously with an antibody to the transferrin receptor (tfr) followed by a Texas red– conjugated secondary antibody, and to GLUT4 (gt) followed by a fluorescein-conjugated secondary antibody. Single confocal images were recorded, separately for each fluorophore, from the surface (left panels) or the core (right panels) of the fibers. The core views were rotated by 90° compared with surface views. In the large depots of the perinuclear belt, there is a large degree of overlapping (yellow) which is exaggerated by saturation of the image. In the smaller depots that are encircled by this belt, there is much less overlap. The small depots are shown, enlarged, in the bottom panel which displays their computer-drawn contours. Most of the depots are small and round. Only a small fraction of these overlap (arrows). Some depots are larger and irregularly shaped. They show a large degree of overlap (arrowheads). Notice, however, that the green and red contours are differently shaped. Bars, 5 μm.