Biochemical characterization of recombinant yeast PPZ1, a protein phosphatase involved in salt tolerance

Francesc Posas, Mathieu Bollen, Willy Stalmans, Joaquín Ariño

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26 Citations (Scopus)


The Saccharomyces cerevisiae gene PPZ1 codes for a 692-residues protein that shows in its carboxyl-terminal half about 60% identity with the catalytic subunit of mammalian and yeast protein phosphatase-1 and that is involved in salt homeostasis. T The complete PPZ1 protein has been succesfully expressed as a soluble glutathione-S-transferase fusion protein. The recombinant protein, after purification by a single affinity chromatography step, displayed phosphatase activity towards a number of substrates, including myelin basic protein, histone 2A and casein, but was ineffective in dephosphorylating glycogen phosphorylase. It was also active towards p-nitrophenylphosphate. The activity was severalfold increased by the presence of Mn2+ ions and by limited trypsinolysis. The enzyme was inhibited by okadaic acid and microcystin-LR at concentrations comparable to what is found for type 1 protein phosphatase although it was much less sensitive to inhibitor-2. The recombinant protein was phosphorylated in vitro by cAMP-dependent protein kinase, protein kinase C and casein kinase-2. Phosphorylation affected preferentially sites located in the amino-terminal half of the protein and did not alter the activity of the phosphatase. © 1995.
Original languageEnglish
Pages (from-to)39-44
JournalFEBS Letters
Issue number1
Publication statusPublished - 10 Jul 1995


  • Bacterial expression
  • Fusion protein
  • Protein phosphatase
  • Saccharomyces cerevisiae


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