Effect of PfI2 on PfPP1 phosphatase activity. A. Scheme of His-tagged recombinant wild-type, deleted and mutated PfI2 proteins used in this study. Recombinant PfPP1 was pre-incubated for 30 min at 37°C with different concentrations of PfI2WT (B), PfI2(1–94) (C), PfI2(19–144) (D), PfI2W16A (E) and PfI2Y103A (F) proteins before the addition of pNPP. Results presented as% of relative increase or decrease are means ± SEM of four independent experiments performed in duplicate.