The La protein functions redundantly with tRNA modification enzymes to ensure tRNA structural stability

PUS4 is required for stable accumulation of the mutant tRNA^Arg_CCG. (A) Wild-type cells (PUS4 TRR4), trr4-1 cells (PUS4 trr4-1), cells containing PUS4 under control of the GAL1 promoter (GAL– PUS4 TRR4), and trr4-1 cells containing PUS4 under control of the GAL1 promoter (GAL–PUS4 trr4-1) were grown at 25°C in galactose-containing media and switched to glucose media at time 0. At intervals, RNA was extracted and subjected to Northern analysis to detect tRNA^Arg_CCG(top) and tRNA^Arg_UCU(bottom). (B) Graphic representation of the data in A. The intensity of each band was determined using a PhosphorImager, and the values for tRNA^Arg_CCG at each time point were normalized relative to the amount of the control tRNA^Arg_UCU. Due to the large differences in intensities, the wild-type (left) and trr4-1 (right) samples were graphed separately.