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

FEBS Lett. 1995 Jul 10;368(1):39-44. doi: 10.1016/0014-5793(95)00593-x.


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. The complete PPZ1 protein has been successfully 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Catalysis
  • Cloning, Molecular
  • Escherichia coli
  • Fungal Proteins / chemistry
  • Fungal Proteins / metabolism*
  • Molecular Sequence Data
  • Oligodeoxyribonucleotides
  • Phosphoprotein Phosphatases / chemistry
  • Phosphoprotein Phosphatases / metabolism*
  • Phosphorylation
  • Protein Phosphatase 1
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / metabolism
  • Saccharomyces cerevisiae / drug effects
  • Saccharomyces cerevisiae / enzymology*
  • Saccharomyces cerevisiae Proteins*
  • Sodium Chloride / pharmacology


  • Fungal Proteins
  • Oligodeoxyribonucleotides
  • Recombinant Fusion Proteins
  • Saccharomyces cerevisiae Proteins
  • Sodium Chloride
  • PPZ1 protein, S cerevisiae
  • Phosphoprotein Phosphatases
  • Protein Phosphatase 1