FIGURE 9.

Effects of N- and C-terminal deletions on hTgs1 methyltransferase activity. A, aliquots (4 μg) of the nickel-agarose preparations of deletion mutants Tgs1-(576–853), Tgs1-(607–853), Tgs1-(631–853), Tgs1-(662–853), and Tgs1-(631–846) were analyzed by SDS-PAGE. Polypeptides were visualized by staining the gel with Coomassie Brilliant Blue dye. The positions and sizes (kDa) of marker proteins are indicated on the left. B, methyltransferase reaction mixtures (20 μl) containing 50 μm [³H-CH₃]AdoMet, 1 mm m⁷GDP, and hTgs1 proteins as specified were incubated for 15 min at 37 °C. The extent of methyl transfer is plotted as a function of input enzyme.