Fig. 7. Localization of Shiga toxin and clathrin heavy chain in K44A and BHK control cells. HeLa (A) and BHK (B) control cells grown with tetracycline for 48 hours and with (+ ba) or without (–ba) 2 mM butyric acid for the last 24 hours were incubated with 1 µg ml^–1 Alexa Fluor 488-labelled Shiga toxin (STx) for 20 minutes. CHC staining was performed by using goat anti-CHC antibodies followed by rhodamine-labelled donkey anti-goat IgG. Quantification of the extent of colocalization between STx and CHC (as the percentage of the total amount of toxin) from eight or nine cells is shown in (A,B, bottom). The error bars represent the standard error of the mean.