Figure 4.

Characterization of specific B⁰AT1 inhibitors. (A, B) Radioactive flux experiments showed that NSC63912 (A) and NSC22789 (B) inhibited Na⁺‐dependent leucine transport in CHO‐BC cells, but did not block the endogenous Na⁺‐independent transporter (n = 5). Inhibition of leucine transport in the FLIPR assay is shown for comparison (closed squares). (C) NSC63912 acts as a competitive inhibitor by affecting the K_M, but not the V_max of the transporter as shown in an Eadie‐Hofstee plot (n = 5). (D) NSC22789, by contrast, selectively reduced the V_max without affecting the K_M and therefore qualifies as a non‐competitive inhibitor (n = 5). (E,F) Chemical structures of NSC63912 and NSC22789. The letter ‘n’ refers to the number of independent experimental repeats for each experimental group.