Description
Okadaic acid is a naturally occuring polyether toxin produced by marine dinoflagellates. It is a potent and selective inhibitor of protein phosphatases, inhibiting PP2A completely at 1nM and PP1 at higher concentrations (IC50=10-15nM). PP2B is much less sensitive to okadaic acid than PP1, while PP2C is not inhibited. This selectivity is the basis for an improved identification and quantification procedure for these enzymes. The hydrophobic backbone of okadaic acid enables it to enter cells where it stimulates intracellular protein phosphorylation. It mimics the effects of insulin, enhances transmitter release at neuromuscular junctions, and causes vasodilation. Okadaic acid is an extremely useful tool for studying cellular processes that are regulated by phosphorylation. It does not affect activity of acid phosphatase, alkaline phosphatase, or tyrosine phosphatase. It induces apoptosis in human breast carcinoma cells (MB-231 and MCF-7) and in myeloid cells, but inhibits glucocorticoid-induced apoptosis in T cell hybridomas. It is a non-phorbol type of tumor promoter. It has shown contractile effects on smooth muscle and heart muscle. It significantly increases cyclin B1 expression in adult neurons