FIG. 4.

Plot of HIS3 marker mobilization (Table 2) against IR50 (Mn²⁺/Mg²⁺ ratio at which WT and suppressor mutant RTs display 50% activity). The 50% RT activities are calculated from logarithmic regressions of the steepest part of the WT and suppressor mutant Mn²⁺ inhibition curves from Fig. 2.