Figure 4.

Intracellular activities of tRNA^Val-enzymes in LTR-Luc HeLa cells. (A) Assay system for measurements of activities of tRNA^Val-enzymes in LTR-Luc HeLa cells and (B) the effects of tRNA^Val-enzymes on the Tat-mediated transcription of the chimeric LTR-Luc gene. tRNA^Val-enzyme(s)- and tat-expression vectors were used at a molar ratio of 2:1 for cotransfection of LTR-Luc HeLa cells. The results shown are the averages of results from five sets of experiments. Luciferase activity was normalized by reference to the efficiency of transfection, which was determined by monitoring activity of a cotransfected gene for β-galactosidase.