Analysis of NtHSP101 translational regulatory activity in yeast mutants affecting individual translation initiation factors. pTPI–NtHSP101 and either pGAL1–Ω-luc (•) or pGAL1–luc (○) were introduced into null and temperature-sensitive mutants affecting translation initiation factors. Transformants first grown to late-exponential stage (whereupon expression from pGAL1–Ω-luc and pGAL1–luc was equivalent) were inoculated into fresh SGM at the zero time point. The expression from pGAL1–Ω-luc, pGAL1–luc, and their expression ratio (i.e., NtHSP101 activity as indicated by the ratio, Ω-luc/luc) are shown below each panel. Analysis of the temperature-sensitive mutants was performed at the permissive (21°C) (F,H,J) and nonpermissive (37°C) (G,I,K) temperatures, where the arrow indicates the time point at which each culture was shifted to 37°C. (WT) parent strain. Strains used for the analysis: CW04 is wild-type for TIF3, CAF20, TIF4631, TIF4632 (A); RCB1-1A is the eIF4B null mutant (tif3) (B); CDK36-1A is the caf20 null mutant (C); YCG318 is the tif4632 null mutant (E); YCG165 is the tif4631 null mutant (D); 4-2 is the eIF4Ets mutant (F,G); 21R is the PRT1 parent strain (H,I); and TP11B-4-1(prt1-1) is an eIF3-p90ts mutant (J,K).