Figure 3.

ASKα Phosphorylates and Thereby Activates G6PD6 in Vitro.

(A) Phosphorylation of G6PD5 and G6PD6 by ASKα. Kinase assays were performed with purified GST-ASKα and GST-G6PD5 or GST-G6PD6. ASKα did not phosphorylate GST alone.

(B) Enzymatic activities of G6PD5 and G6PD6. G6PD activity was quantified after a phosphorylation reaction of GST-G6PD5 and GST-G6PD6 without kinase or with GST-ASKα or with GST-ASKα K98R. Data are means ± relative sd. The assay was performed three times using fresh proteins from independent purifications. Asterisks indicate a significant difference (***P < 0.005) tested by Student’s t test for pairwise comparison to the unphosphorylated control.