FIG. 7.

Time course of l-leucine-induced transcription of PTR2 and CAR1. A liquid culture of strain HKY77 carrying plasmid pHK048 (SSY5-c-myc) was grown in SD to an OD₆₀₀ of 0.5, and the culture was split into two parts (t = 0). One-half of the cell culture received an aliquot of l-leucine (+leu; lanes 2 to 6) to a final concentration of 1.3 mM, and the other received an equal volume of water (−leu; lanes 7 to 11). Both cultures were incubated at 30°C for an additional 180 min, and at the times indicated, subsamples were withdrawn and total RNA was isolated. The levels of PTR2 (A) and CAR1 (B) expression were analyzed by Northern blotting (upper panels), and after background correction, signal strengths (arbitrary units) relative to the levels of actin mRNA (ACT1) were quantitated (lower panels).