CTA1 activity in the absence or presence of ARF6.
For both panels, toxin activity against a diethylamino(benzylidine-amino)guanidine (DEA-BAG) substrate was detected from the increase in fluorescent units.
A. Two-fold dilutions of CTA1 were incubated at 25°C with ARF6/GTP (filled circles), ARF6/GDP (open circles), or in the absence of ARF6 (squares). Data are presented as the means ± standard errors of the means (SEMs) of 8 samples from two independent experiments.
B. Two-fold dilutions of CTA1 were incubated at 37°C in the presence of ARF6/GTP. Open squares represent toxin samples that were pre-incubated with ARF6/GTP at 25°C before warming to 37°C; filled squares represent toxin samples that were heated to 37°C for 30 min before the addition of ARF6/GTP. Data are presented as the means ± SEMs of 12 samples from three independent experiments.