Cells were fixed with 4% paraformaldehyde (10 min at room temperature) followed by permeabilization with 0.1% Triton X-100 for 10 min. Cells were washed three times with PBS/3%BSA and blocked for 20 min with the same solution. The endoplasmic reticulum was visualized using mouse anti-calnexin AF18 (Abcam) and goat anti-mouse Cy3 labeled antibody (Dianova), the Golgi apparatus was visualized using rabbit anti-α-Mannosidase II [83 (link)] and goat anti-rabbit Cy3 labeled antibody (Dianova). The IBs were detected with mouse anti-c-myc 9E10 (Santa Cruz Biotechnology) and goat anti-mouse Cy3 labeled antibody (Dianova) or directly with goat anti-c-myc FITC conjugated antibody (Novus Biologicals). Flag-HA-tagged polySTs were detected with mouse anti-FLAG M5 (Santa Cruz Biotechnology) and goat anti-mouse Cy3 or goat anti-mouse FITC labeled antibody. Primary antibodies were incubated for 2 h and secondary antibodies for 1 h (diluted in 3% BSA/PBS) at room temperature. In between, cells were washed 5 times with PBS-0.05%Tween. For analysis by laser scanning confocal microscopy, cells were coated with Vectashield Mounting Medium (Vector Laboratories).
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