Fig. 1. Fusion of a post-Golgi vesicle near the leading edge imaged by TIR-FM. NRK fibroblasts were microinjected with cDNA encoding LDLR-GFP and the newly synthesized proteins allowed to accumulate in the Golgi at 20°C. The cells were then imaged by epifluorescence (A) and TIR-FM (B) 10 minutes after the shift to 32°C. Scale bar, 10 µm. Using epifluorescence, the accumulated LDLR-GFP brightens the area of the Golgi complex. Using TIR-FM on the same cell, single vesicles can be seen that have arrived at the contact surface. (C) An enlargement of a vesicle moving toward the leading edge and (D) fusing with the plasma membrane. Scale bars, 2 µm (C), 1 µm (D). (E) Plots of the total intensity and the width of the fluorescence intensity of the fusion event in (D). Time is indicated relative to moment of fusion start at 0.00 seconds.

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