FIGURE 3.

Effect of inhibitors on the [³H]NAD⁺/NAD⁺ exchange by reconstituted AtNDT1 and AtNDT2. Proteoliposomes were preloaded internally with 10 mm NAD⁺. Transport was initiated by adding 0.6 and 0.15 mm [³H]NAD⁺ for AtNDT1 (white bars) or AtNDT2 (black bars), respectively. The reaction time was 2 min (AtNDT1) and 45 s (AtNDT2), respectively. Thiol reagents were added 2 min before the labeled substrate; the other inhibitors were added together with the labeled substrate. The final concentrations of the inhibitors were 20 mm (PLP, pyridoxal 5′-phosphate; BAT, bathophenanthroline), 0.2 mm (MER, mersalyl; p-HMB, p-hydroxylmercuribenzoate; p-HMBS, p-hydroxymercuribenzensulfonate), 25 μm HgCl₂, 2 mm (BM, butylmalonate; BTA, 1,2,3-benzenetricarboxylate), 0.3 mm (BrCP, bromcresol purple), 1 mm (NEM, N-ethylmaleimide; CCN, α-cyano-4-hydroxycinnamate), 0.2% (TAN, tannic acid), and 10 μm (BKA, bongkrekic acid; CAT, carboxyatractyloside). The extents of inhibition (%) for each carrier from a representative experiment are given.