(A) Knock down of eEF1A1 diminishes HSP70 mRNA stability. Actinomycin D (Ac) was added 30 min after the onset of heat shock. The level of HSP70 and GAPDH mRNA at this time point was taken as 100%. Data are represented as mean ± SEM from two experiments. (B) eEF1A1 binds to stem-loop 2 of the HSP70 3′UTR as determined by EMSA. Indicated concentrations of purified eEF1A1 were incubated with 20 kcpm of in vitro transcribed, end labeled HSPA1A 3′UTR RNA (∼0.1 pmol/µl) for 30 min at room temperature. Probe Wt refers to HSPA1A 3′UTR sequence, ΔSL1 is the deletion of nt 7–34, ΔSL2 is the deletion of nt 83–93, 151–158, ΔSL3 is the deletion of nt 217–226, 246–255. M-fold predicted structure for HSPA1A 3′UTR is shown. The stem-loops are marked SL1, SL2, and SL3. The deletion regions are indicated by red rectangles. (C) Determination of the dissociation constant for eEF1A1-HSP70 3′UTR. Experiment was performed as in B.