Figure 5.

Specificity of B⁰AT1 inhibitors. (A) NSC63912 and NSC22789 at a concentration of 300 μM, were used to test for inhibition of leucine transport in X. laevis oocytes expressing B⁰AT1 and collectrin. The same inhibitors (300 μM) were tested in 143B osteosarcoma cells (B), where Na⁺‐dependent glutamine transport is largely mediated by ASCT2 (n = 5), and in MCF‐7 cells (C) where Na⁺‐independent transport of leucine is largely mediated by LAT1 (n = 5). Moderate inhibition was observed in both cell lines. Substrate analogues such as S‐benzyl‐L‐cysteine and BCH, by contrast, fully blocked leucine transport in MCF‐7 cells. (D) Both compounds also inhibited Na⁺‐dependent leucine transport in inverted sections of mouse intestine an in situ preparation with significant B⁰AT1 activity (n = 5). * P < 0.05, significantly different from control; n refers to the number of independent experimental repeats for each experimental group.