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Protein phosphatase type 2C active at physiological Mg 2+ : stimulation by unsaturated fatty acids
Author(s) -
Klumpp Susanne,
Selke Dagmar,
Hermesmeier Jan
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)01237-x
Subject(s) - stimulation , phosphatase , chemistry , biochemistry , biology , enzyme , endocrinology
Type 2C serine/threonine protein phosphatases (PP2C) so far require unphysiologically large amounts of Mg 2+ ions for activity. Activators and inhibitors are not available, targeting subunits unknown. Studying the regulation of PP2C isozymes in bovine retinae, we found that the activity of PP2C increased specifically by the addition of mono‐ and polyunsaturated fatty acids. Activation was most pronounced at low Mg 2+ levels (10‐fold stimulation of PP2Cα by 0.5 mM arachidonic acid at 0.7 mM Mg 2+ ). Sensitivity of PP2Cβ was 30–50% less, revealing for the first time enzymatic differences among the PP2C isozymes. Combining unsaturated fatty acids with physiological Mg 2+ concentrations resulted in PP2C activity that by far exceeded the dephosphorylation rates obtained otherwise. This suggests that PP2C activity has been severely underestimated in the past. In the presence of fatty acids, Ca 2+ ions became inhibitory in the micromolar range. We conclude that unsaturated fatty acids may play a role in the regulation of PP2C activity.