Figure 7. ⁶³Ni²⁺ uptake of W288 mutants.

A. To determine maximal ⁶³Ni²⁺ uptake, cells were incubated for 10 min with 0.3 μCi ⁶³Ni²⁺ per tube with a total [Ni²⁺] of 125μM. Uptake in the presence of 10 mM Mg²⁺ (~600 cpm) was taken as background and subtracted from total uptake to give net cpm uptake. The data are representative of at least two independent experiments done in triplicate. B. Mg²⁺ dose response curve. C. Co²⁺ dose response curve. D. Ni²⁺ dose response curve. Each curve is normalized to uptake for that mutant in the absence of competing cation. Data are representative of at least three independent experiments done in triplicate. Error bars are not shown for clarity but were similar to those shown in Figure 3. Maximal uptake for these mutants ranged from ~3,000 to 8,000 cpm.