Table 4.

Transcription of AGP1 is induced in response to external amino acidsa

LineStrainNitrogen sourceIntracellular tryptophan (nmol · mg−1 [dry wt])β-Galactosidase activity (nmol · min−1 · mg of protein−1)
1Wild typeUrea0.15≤2≤2
2 trp2f b r Urea10≤293
3 gap1-92 agp1-1 Urea0.09≤2≤2
Urea plus Trp (90 min)1256080
  • a Strains 23346c (ura3), RE1 (trp2fbr ura3), and 30622a (gap1-92 agp1-1 ura3) harboring the CEN-based plasmids YCpAGP1-lacZ or YCpARO9-lacZ were grown on minimal medium with urea (5 mM) as the sole nitrogen source. Tryptophan was added at a 5 mM final concentration where indicated. The reported β-galactosidase activities are means of two independent experiments. The values of intracellular tryptophan concentrations are means of three experiments.