Table 1.

Inhibition of PP-1C by phospho-DARPP-32, phospho-inhibitor-1, and related synthetic phosphopeptides

PP-1C activity was measured as described using 10 μM [³²P]phosphorylase a as substrate and concentrations of phosphorylated inhibitors that bracketed the IC₅₀ value. The phosphorylated threonine is underlined. The results shown for the last two peptides were obtained from a different series of studies. Phospho-D32[1–38c] was assayed again as an internal control.