FIGURE 6.

Methylated product analyses of PRMT7 mutants with the H2B(23–37) peptide as a substrate. Peptide (12.5 μm) was methylated by a 0.48 μm concentration of the indicated GST-PRMT7 mutant (A–G) with [³H]AdoMet (0.7 μm) in a 60-μl reaction for 18 h. The products were acid-hydrolyzed and subjected to cation exchange coupled with amino acid analysis as described in the legend to Fig. 2. The red line shows radioactivity with the full reaction mixture; the blue line shows the radioactivity in enzyme automethylation (no H2B(23–37) was present). For ease of comparison, the data for wild-type GST-PRMT7 (H) are combined from the data shown in Fig. 2A and Fig. 3I. In H, the reaction was incubated for 20 h but under conditions otherwise identical to those shown in A–G, where the incubation was 18 h.