FIGURE 9.

Functional properties of Can1(E184A) and Can1(E184Q) mutants. A, strain 22Δ8AA transformed with a plasmid expressing either Can1(E184Q) or Can1(E184A) mutant was grown on glucose-ammonium medium and examined by fluorescence microscopy. B, strain 21983c (gap1 can1) was transformed with the empty vector YCpFL38, the pKG001 (YCp-CAN1) plasmid expressing the wild-type Can1, or one of the two derived plasmids encoding either Can1(E184Q) or Can1(E184A) mutants, and grown on solid minimal medium with arginine (Arg) or ammonium (Am) as the sole nitrogen source and with canavanine (Can) when indicated. Cells were incubated at 29 °C for 3 days. In conditions of non-growth, the white streaks on the squares correspond to light reflections on the agar and not to cell growth. C, initial rates of [¹⁴C]arginine (10 μm) uptake by wild-type Can1 and Can1(E184Q) or Can1(E184A) mutants expressed in the 22Δ8AA strain grown on minimal ammonium medium. Error bars, S.E.; n = 2. When not visible, error bars are smaller than the symbols. prot, protein.