Figure 3.

AtNramp3 and AtNramp4 complement a Fe uptake deficient yeast mutant. Growth of fet3fet4 yeast cells expressing AtNramp1, AtNramp3, or AtNramp4 or IRT1 on synthetic dextrose-URA (pH 5.5) (A) or (pH 6) (B) supplemented 0.2 mM FeCl₃ (Upper) or without added Fe (Lower). fet3fet4 yeast cells were transformed with the empty pDR195 vector, with pDR195 containing the cDNA of AtNramp1, AtNramp3, or AtNramp4, or with the vector pFL61 containing the IRT1 cDNA. Transformed strains were grown overnight in liquid synthetic dextrose-ura supplemented with 0.2 mM FeCl₃. The cultures were diluted to ODs of 10⁻¹ to 10⁻⁵ (as indicated) and spotted on synthetic dextrose-ura plates. The plates were incubated at 30°C for 3 days before photography. (C) FeII uptake rates in fet3fet4 yeast expressing AtNramp3 or transformed with the empty vector. FeII accumulation was measured after 10 min in 30 μM ⁵⁵Fe at pH 5.5.