Protein phosphatases 1 and 2A and their naturally occurring inhibitors: current topics in smooth muscle physiology and chemical biology

Table 1 Inhibition of PP1 and PP2A by some naturally occurring inhibitors

The dissociation constants (K _i) for the interaction of PP1 and PP2A with the naturally occurring inhibitors referred to in this review are listed. The values are in nM, unless otherwise stated. The difference between K _i and ID₅₀ is usually negligible for inhibitors with relatively low affinity (say, K _i > 100 nM)
n.d. not determined
^aUnpublished K _i data of A. Takai
^bID₅₀ instead of unavailable K _i data. The references in parentheses present ID₅₀, which is generally dependent on the concentration of phosphatase in the assay (see Takai and Mieskes [80])
^c,dAlso called nodularin-R and nodularin-V, respectively

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