Interaction of the catalytic subunits of protein phosphatase-1 and 2A with inhibitor-1 and 2: A fluorescent study with sulfhydryl-specific Pyrene maleimide

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The catalytic subunits of protein phosphatase-1 and 2A were covalently modified in their reactive sulfhydryl groups with N-(3-Pyrene) maleimide resulting in fluorescent labeling of the proteins to an extent of 0.85 and 0.9 mole dye/mole enzyme, respectively. The reaction of the sulfhydryl group led to the partial inactivation of both phosphatase-1 and 2A. Inhibitor-1 and inhibitor-2 increased markedly the fluorescence intensity of the dye-phosphatase-1 conjugate implying that the labeled enzyme retained its ability to bind these proteins. In contrast, inhibitor-1 or inhibitor-2 had no influence on the fluorescence of the dye-phosphatase-2A conjugate. No change in either the fluorescence intensity or polarization of labeled phosphatase-1 and 2A was observed in the presence of thiophosphorylase a, suggesting a lack of interaction of these enzyme forms with the substrate after modification of the reactive sulfhydryl group.

Original languageEnglish
Pages (from-to)559-564
Number of pages6
JournalBiochemical and biophysical research communications
Issue number2
Publication statusPublished - Jun 15 1990


ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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