Figure 3.

Ion binding is compromised in functionally impaired DAT variants. Sodium dependence (A) and chloride dependence (B) of [³H]dopamine uptake are shown. Choline chloride and sodium gluconate were used for equimolar cation and anion substitution, respectively. I312F, T356M, and D421N all show distinct changes in ion coordination. The derived K_d values for Na⁺ and Cl⁻ are listed in Table 3. All curves are normalized and presented as mean ± S.E. from three (all variants) or six (WT) experiments, each performed in triplicate.