Fig. 2

System y⁺L activity in lymphoblasts carrying the same mutations as LPI₁ and LPI₃. Panel a. Arginine transport was measured in lymphoblasts obtained from healthy donors (cont, n = 4) and LPI patients carrying LPI₁ and LPI₃ mutations (see “Materials and Methods”). Arginine uptake was assayed by 1-min incubation in EBSS supplemented with L-[³H]-arginine (50 μM; 2 μCi/ml), either in the absence or in the presence of 2 mM leucine (see Methods). For controls, data are means ± SEM of four different subjects; for LPI, data are means ± SEM of three independent experiments performed in cells obtained from the same subject. Panel b. Data shown in Panel a were employed to calculate the relative contribution of system y⁺L as the difference between total transport and transport measured in the presence of leucine (see Methods)