Figure 3.

tatCN21 inhibits stimulated and autonomous CaMKII activity with equally high potency and efficacy. A, tatCN21 potently inhibited Ca²⁺/CaM-stimulated CaMKII (2.5 nm) activity toward the peptide substrate syntide 2 (75 μm). The calculated IC₅₀ was ∼40 nm. B, tatCN21 inhibited stimulated and autonomous CaMKII activity with equal potency (as indicated by identical inhibition at 40 nm, the IC₅₀ calculated from A) and efficacy (as indicated by complete block of inhibition at 5 μm, 120-fold of IC₅₀), while stimulated activity of the related CaMKIV was not affected at all. Error bars indicate SEM in all panels.