Fig. 3. Appearance of Rab3A and Rab27A on immature secretory granules during granule biogenesis and maturation. (A) PC12 cells were transfected with ppANF-EGFP, EGFP-Rab3A or EGFP-Rab27A and cultured for 18 hours at 20°C to block granule budding at the TGN and then fixed (time 0) or incubated for 30 minutes at 37°C to allow budding of immature granules. (B) PC12 cells were co-transfected with ppANF-EGFP and mRFP-Rab3A or mRFP-Rab27A, cultured for 18 hours at 20°C and then fixed at the indicated times after incubation at 37°C. The images show overlays of ppANF-EGFP fluorescence in green and mRFP fluorescence in red. Expanded inserts are shown for the 10- and 30-minute time points to show lack of colocalisation at 10 minutes and colocalisation at 30 minutes. Bars, 4 µm.