FIGURE 6.

Methyl acceptor specificity of hTgs1. Methyltransferase reaction mixtures (20 μl) containing 50 μm [³H-CH₃]AdoMet, 4 μg of hTgs1-(576–853), and 2.5 mm cap dinucleotide (A) or nucleoside diphosphate (B) as specified were incubated for 15 min at 37 °C. Nucleotide was omitted from the control reaction in lane -. Aliquots (4 μl) were spotted onto PEI-cellulose TLC plates. The anionic nucleotides were resolved from AdoMet by ascending TLC in 50 mm ammonium sulfate. The chromatograms were treated with Enhance (PerkinElmer Life Sciences), and ³H-labeled material was visualized by autoradiography. The methyltransferase reaction products m^2,7GpppG and m^2,7GpppA (A) or m^2,7GDP (B) are denoted by ◂.