Figure 8.

Ribosome-binding mutant traps HAC1^u on the depurinated ribosome. A, analysis of total HAC1, HAC1^u, and HAC1ⁱ on the ribosome by qRT-PCR using RNA extracted from ribosomes purified from yeast grown in the absence (Gal) or presence of ER stress (Gal + DTT) compared with the same cells grown in dextrose. Note that values shown for HAC1ⁱ are reduced by 10-fold for presentation on the same bar graph as total and HAC1^u mRNA. The y axis shows mean fold change in HAC1 mRNA, with error bars representing the range of abundance from three biological replicates using three technical replicates for each. Statistical analysis was done separately for each HAC1 mRNA. Means with different letters show significant differences according to the LSD test (p < 0.01). B, depurination level of ribosomes isolated from yeast carrying VC, WT, or mutant RTA grown in dextrose and galactose in the absence (Gal) or presence of ER stress (Gal + DTT) quantified by qRT-PCR. The y axis shows mean fold change in ribosome depurination compared with VC with S.E. representing range of depurination from three biological replicates using three technical replicates for each. Statistical analysis was done using the means from each HAC1 mRNA. Means with different letters show significant differences according to the LSD test (p < 0.01).