Figure 2. Kinetic patterns of synchronized transport of albumin and PC-I through the Golgi stack.
Human fibroblast cells were microinjected in the nucleus with cDNA for albumin and incubated for 2 hr before further treatments. Transport was synchronized according to the CHX/32-15°C protocol and the cells were examined by immunofluorescence and immuno-EM. (A) Immunofluorescence localization of albumin and PC at the end of the 15°C block. The area in (A) indicated by white rectangle is enlarged in (B) (C–E). Co-localization between albumin (C) or PC (D) or of both cargoes (E) with TGN46, 3 min after release of the block. (F–G). Localization of PC (F) and albumin (G) 3 min after release of the 15°C block by immuno-EM. PC (indicated by *) localizes selectively to the cis-cisterna. The cis-side of the Golgi is revealed by the presence of GM130 labeled by immuno-nanogold technique (indicated by white arrows) (F). Albumin labeled by immuno-nanogold technique (black dots) shows a diffuse localization throughout the Golgi complex (G). Bars: 5 μm (A), 2 μm (B–E), 125 nm (E and F).