The microcystins and nodularins: cyclic polypeptide inhibitors of PP1 and PP2A.

The serine/threonine phosphatases are inhibited by a variety of natural toxins, including the microcystins and nodularins. Progress in understanding the details of the biosynthetic origin and the binding of these compounds is discussed, as is the progress made in synthesizing the members of these families. Additionally, the work by several groups to either synthesize simplified analogues that are still potent, or introduce selectivity for PP1 over PP2A are discussed. Finally, the properties of a series of five new truncated analogues are examined.