Bioactivity: Okadaic acid ammonium salt, a marine toxin, is an inhibitor of protein phosphatases (PP) . Okadaic acid ammonium salt has a significantly higher affinity for PP2A ( IC 50 =0.1-0.3 nM), and inhibits PP1 ( IC 50 =15-50 nM), PP3 ( IC 50 =3.7-4 nM), PP4 ( IC 50 =0.1 nM), PP5 ( IC 50 =3.5 nM), but does not inhibit PP2C. Okadaic acid ammonium salt increases of phosphorylation of a number of proteins by inhibiting PP, and acts as a tumor promoter. Okadaic acid ammonium salt induces tau phosphorylation.
