Fig. 3: The law of demand drives amino acid restoration-prioritization responses as observed for arginine.

A A hypothetical supply price vs required demand graph for the glutamate derived amino acids, as based on the law of demand. B Gcn4 response after complete amino acid withdrawal (-AA), or for individual amino acid (Arg, Pro, Lys) dropouts. Relative protein amounts are shown below the representative blot, and comparisons are to +AA. n = 3, biological replicates. C Relative difference in the growth of wild-type and gcn4∆ cells in the indicated amino acid group dropout or complete medium, as estimated after 6 hours. n = 3, biological replicates, comparisons are to +AA for WT and gcn4∆ sets. D A summary of predicted Gcn4 responses in arg1∆ (arginine auxotrophic) cells, based on the estimated metabolic and proteome demand for arginine. Since the polyamine contribution towards the arginine demand is high, upon restoring polyamines a reduction in Gcn4 would be predicted. E The extent of the Gcn4 response upon arginine deprivation, in arginine auxotrophic cells. The experimental setup is illustrated. The image shows a representative blot for Gcn4 amounts in arginine replete, drop-out, and restored conditions. n = 4, biological replicates. F The contribution of polyamine synthesis towards the demand for arginine. A representative blot indicating the Gcn4 amounts in minimal medium, or after spermidine (polyamine) supplementation. The experimental set-up is illustrated. n = 3, biological replicates. All panels show quantifications displayed as mean ± SEM. Two-tailed student’s t-test, ****p < 0.0001, ns denotes non-significant difference. Data are provided in Source Data file.