Kinase activity of PfeIK1. A: GST-PfeIK1 phosphorylates the exogenous substrates α-and β-casein. Kinase assays were performed using 10 μg α-casein (left 3 lanes) or β-casein (right 3 lanes), in the presence of 2 μg wild-type kinase catalytic domain (WT), catalytically inactive mutant (K458M) or no kinase (-). Upper panel: autoradiogram, lower panel: Coomassie blue-stained gel. B: GST-PfeIK1 autophosphorylates and can phosphorylate recombinant GST-PfeIF2α, but not the mutant GST-PfeIF2α-S59A. Kinase assays were performed using 2 μg wild-type PfeIK1 catalytic domain (WT), or catalytically inactive mutant (K458M), or no kinase (-), in the presence of 10 μg wild-type GST-PfeIF2α (left 3 lanes), targeted mutant GST-PfeIF2α-S59A (middle 3 lanes) or no substrate (right 2 lanes). The position of the substrate is highlighted by ovals.