FIGURE 1.

Constitutively targeted Golgi-β₁γ₂ converts the Golgi into small vesicles. A, Myc-tagged β₁ or β₅ were expressed in HeLa cells along with wild-type or mutant γ₂ in the following combinations, as indicated: Myc-β₁ and γ₂ (β₁γ₂), Myc-β₅ and γ₂ (β₅γ₂), Myc-β₁ and Cyto-γ₂ (Cyto-β₁γ₂), Myc-β₁ and ER-γ₂ (ER-β₁γ₂), Myc-β₁ and PM-γ₂ (PM-β₁γ₂), Myc-β₁ and Golgi-γ₂ (Golgi-β₁γ₂), and Myc-β₅ and Golgi-γ₂ (Golgi-β₅γ₂). Cells were visualized by immunofluorescence microcopy using anti-Myc, anti-GM130, or anti-TGN46 to detect β, the cis-Golgi stacks, and the trans-Golgi stacks, respectively. Arrows indicate intact Golgi. The inset shows vesiculated Golgi. Scale bar, 10 μm. B, results from A were quantitated and plotted as the percentage of cells with a fragmented Golgi. 100 cells from each of 6 different experiments were counted as having intact or fragmented Golgi. The percentage of cells with fragmented Golgi was >75% in β₁γ₂-expressing cells and >90% in Golgi-β₁γ₂-expressing cells, whereas in control transfections (empty vector) fragmented Golgi was observed in 10% of cells (not shown). Statistical significance as compared with control was tested using unpaired t test (*, p < 0.001).