Microcystins liver damage

Microcystin. An example of this type of toxin is microcystin (produced by blue-green algae), which binds covalently to a phosphatase inside liver cells this toxin does not damage other cells of the body. Unless uptake of the toxin by the liver is blocked, irreversible damage to the organ occurs within 15 to 60 minutes after exposure to a lethal dose. When this happens, the tissue damage to the liver is so severe that therapy may have little or no value. For microcystin, unlike most toxins, the toxicity is the same, no matter what the route of exposure. 

Microcystins potently inhibit serine/threonine protein phosphatases that dephosphorylate other proteins, an action akin to an on/off switch. The novel hydrophobic amino acid ADDA is essential to its bioactivity. Its action also promotes the formation of tumors. The liver is particularly susceptible to these toxins because unlike many other cell types, these peptides readily penetrate liver cells and are specifically taken up through the bile acid transport pathway. These toxins damage the liver by affecting the maintenance by these phosphatases of the cyto-skeleton, a network of protein filaments. Protein phosphatases degrade the colorless p-nitrophenyl phosphate into a yellow product and this has been... 

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