Figure 7. Movement of vesicles long distances prior to fusion is observed infrequently.

Adipocyte transfected with mCherry-IRAP-pHluorin was serum-starved prior to stimulation with 100 nM insulin. Images were acquired using TIRF microscopy at an acquisition rate of 20 frames per 1 s, and a kymograph was generated. mCherry (magenta) allows visualization of the vesicle prior to fusion with the plasma membrane, at which time the pHluorin (green) intensity increases. The overlay of magenta and green appears white. The vesicle on the right represents an example of a rare vesicle fusion event that is preceded by a long-distance movement. On the left, a second vesicle approaches the surface in the same vicinity as the first but fuses without detected lateral movement.