FIGURE 2.

Growth of yeast strains in different nitrogen sources. Growth in minimal synthetic medium containing ammonium, arginine, or ornithine as the sole nitrogen source is shown. A, yeast strains transformed with a either an empty plasmid (p) or expressing catalytically active or inactive (inositol phosphate binding domain-disrupted) Arg82. Growth assays were performed in solid medium as indicated in Fig. 1A. B, quantification of the growth rate in arginine and ornithine with respect to the maximum achieved in ammonium for the indicated strains. The growth rate was quantified as the average of the highest slopes of five growth curves. Error bars correspond to S.D. C, yeast strains bearing deletions of genes encoding either inositol-polyphosphate multikinase (Arg82), phospholipase C (Plc1), inositol-hexakis- and -heptakisphosphate 6-kinase (Kcs1), or a combination of the above. Growth assays were performed in solid medium as indicated in Fig. 1A.