Figure 2.

Human ferroportin preferably transports Fe²⁺over other divalent metal ions. (A) Transport activity of Co²⁺, Ni²⁺, and Mn²⁺ using the calcein-based assay (as in Figure 1). Addition of these divalent metal ions is indicated above the curves. All metal ions are provided at the concentration of 100 μM. (B) Comparison of the apparent K_M of ferroportin-mediated transport of different metal ions, with the y-axis break at 0.1 μM. (C) Competition of other divalent ions (Zn²⁺, Cd²⁺, Ca²⁺, and Mg²⁺) against Fe²⁺ transport. Fe²⁺ and the competing metal ions are provided at the concentrations of 10 μM and 100 μM, respectively.