Okadaic acid

An ionophore-like polyether derivative of a C₃₈ fatty acid compound isolated from the dinoflagellates that have fed on the marine sponge Halinchrondria okadai. It is a potent non-comepetitive, reversible inhibitor of serine/threonine-specific protein phosphatases 1 (PP1, IC₅₀ = 10-15 nM, rabbit skeletal muscle, catalytic subunit) and 2A (PP2A, IC₅₀ = 0.1 nM, rabbit skeletal muscle, catalytic subunit). It has only a trivial effect on protein phosphatase 2B (IC₅₀ = 5 µM), a Ca²⁺/calmodulin-dependent enzyme, while PP2C, a Mg²⁺ dependent enzyme, is unaffected. Okadaic acid has no significant effect on the activities of tyrosine phosphatases, alkaline phosphatase, acid phosphatase, and inositol trisphosphatase. It is also a non-phorbol ester-type tumor promoter on mouse skin. Useful for the study of protein phosphatases and of PP1/PP2A in cell extracts, as well as in intact cells. Induces apoptosis in human breast carcinoma (MB-231 and MCF-7) and in myeloid cells, but inhibits glucocorticoid-induced apoptosis in T-cell hybridomas. Has marked contractile effect on smooth muscles and heart muscles. Implicated as a causative agent of diarrhetic shellfish poisoning.

Cell permeable: no

Primary Target
Protein phosphatase

Product does not compete with ATP.

Reversible: no

Target IC₅₀: 10-15 nM and 0.1 nM against protein phosphatase 1 and protein phosphatase 2A, respectively

Packaged under inert gas

Following reconstitution, aliquot and freeze (-20°C). Stock solutions are stable for up to 1 month at -20°C.

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Toxicity: Toxic (F)