Figure 3. L-Arg depletion induces EDEM1 expression and 20S proteasome activity. (A) Jurkat and activated T cells were incubated with (C) and without L-Arg for selected times and the expression of EDEM 1 was determined by western blot. ACTB was used as a loading control. Data shown are representative of three experiments performed. (B) 20S proteasome activity was measured in 20 µg of protein extract of Jurkat and activated T cells incubated with (C) and without L-Arg for the indicated times, in the absence or presence of the proteasome inhibitor lactacystin (10 μM), and performed in triplicate. 20S proteasome activity was measured as the hydrolysis of the fluorogenic peptidyl substrate LLVY-AMC, and reported as μmol/l AMC per mg protein per hour. Data are means ± SD of three independent experiments performed in triplicate.