How phosphorylation activates the protein phosphatase-1 • inhibitor-2 complex

► Phosphorylation of protein phosphatase-1 (PP1) inhibitor-2 (I2) activates PP1-I2. ► The intrinsically disordered I2 phosphorylation region was modeled using NMR data. ► Molecular dynamics revealed phosphorylation induced structural alterations. ► I2 phosphorylation increased frequencies three initial steps of PP1-I2 activation. ► I2 phosphorylation-induced rapid movements were transmitted to the PP1 active site.