Fig. 6. Transport of PC-FP through the early secretory pathway is dependent on the function of the COPI and COPII coat complexes. (A,B) Cells expressing PC-FP were microinjected with a control plasmid (pcDNA3.1 (A); arrowheads indicate examples of TCs) or plasmid expressing SAR1a^(H79G) (B) and incubated at 37°C for 2 hours followed by addition of ascorbate. Images were taken 30 minutes after ascorbate addition. Efficacy of injected SAR1a^(H79G) expression was confirmed by anti-ERGIC-53 labelling (not shown). Control cells (A) were located on the same dish as SAR1a^(H79G) expressing cells (B) for these experiments. (C,D) Cells expressing PC-FP were microinjected with a control plasmid (C; arrowheads indicate examples of TCs) or plasmid expressing pARF1^(Q71L) (D). Ascorbate was added to the medium 4 hours after microinjection. Cells were imaged 30 minutes after the addition of ascorbate. (E,F) Microinjection of anti-EAGE blocks transport of PC-FP through the early secretory pathway. Cells expressing PC-CFP were injected with anti-EAGE in the absence of ascorbate and subsequently incubated with ascorbate for 1 hour following microinjection of anti-EAGE. (E) shows the cell before injection, (F) shows the same cell 1 hour after antibody injection. Note the differences in the ER labelling pattern showing the viability of the cell after injection. Bars=5 µm.

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