Cyclic heptapeptide toxin isolated from the freshwater cyanobacteria, Microcystis aeruginosa. Potent inhibitor of protein phosphatase 1 (PP1) and protein phosphatase 2A (PP2A). Unlike Okadaic Acid (Cat. No. 495604), microcystin-LR is effective on both PP1 (IC₅₀ = 1.7 nM) and PP2A (IC₅₀ = 40 pM). Reacts with phosphatase in a two-step mechanism involving rapid binding and inactivation of the catalytic subunit followed by slower covalent interactions. Has no effect on protein kinases, making it useful for reducing contaminating phosphatase activities in protein kinase assays.

Cell permeable: no

Primary Target
protein phosphatase 1 (PP1) and protein phosphatase 2A (PP2A)

Product does not compete with ATP.

Reversible: no

Target IC₅₀: 1.7 nM, 40 pM, against protein phosphatase 1 (PP1), protein phosphatase 2A (PP2A), respectively

Packaged under inert gas

yes

Toxicity: Highly Toxic (H)

A 2.5 mM (250 µg/100 µl) solution of Microcystin-LR, Microcystis aeruginosa (Cat. No. 475815) in DMSO.

Following initial thaw, aliquot and freeze (-20°C).

Craig, M., et al. 1996. Biochem. Cell Biol. 74, 569.
Nishiwaki, R., et al. 1994. Cancer Lett. 83, 283.
Amick, G.D., et al. 1992. Biochem. J.287, 1019.
Davidson, H.W., et al. 1992. J. Cell Biol.116, 1343.
Nishiwaki-Matsushima, R., et al. 1992. J. Cancer Res. Clin. Oncol. 118, 420.
Cohen, P., et al. 1990. Trends Biochem. Sci.15, 98.
MacKintosh, C., et al. 1990. FEBS Lett.264, 187.
Cohen, P., et al. 1989. FEBS Lett.250, 596.
Carmichael, W.W. 1988. in Handbook of Natural Toxins3,Marine Toxins and Venoms (Tu, A.T., Ed.) p. 121, Decker, New York.

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Not available for sale outside of the United States.

CALBIOCHEM is a registered trademark of Merck KGaA, Darmstadt, Germany