Mutation of the individual Tf lobes increases Tf saturation without altering serum iron. (A) Total iron-binding capacity was decreased upon loss of iron binding to either lobe of Tf compared with WT. (B) Tf saturations in Tf^N-bl/N-bl and Tf^C-bl/C-bl mice were significantly higher than those in WT but not significantly different from each other. (C) No significant differences in serum iron concentrations were observed across the 3 strains. For panels A-C, n = 14 mice per sex for WT and 7 to 8 males and 13 females per group for mutant mice, respectively. (D) Both Tf^N-bl/N-bl and Tf^C-bl/C-bl mice demonstrated increased non–Tf-bound iron concentrations compared with WT. For panel D, n = 2 to 3 female mice per group and n = 4 to 5 male mice per group. Data are presented as Tukey box and whisker plots. Statistical significance was analyzed by ANOVA. **P ≤ .01, ***P ≤ .001, ****P ≤ .0001. ns, nonsignificant.