Direct metal analyses of Mn2+-dependent and -independent protein phosphatase 2A from human erythrocytes detect zinc and iron only in the Mn2+-independent one

Yasumasa Nishito, Hirofumi Usui, Kyoko Shinzawa-Itoh, Rintaro Inoue, Osamu Tanabe, Terumasa Nagase, Takehiko Murakami, Masao Takeda

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20 Citations (Scopus)


A Mn2+-dependent protein phosphatase 2A which is composed of a 34 kDa catalytic C' subunit and a 63 kDa regulatory A' subunit, was purified from human erythrocyte cytosol. C' and A' produced V8- and papain-peptide maps identical to those of the 34 kDa catalytic C and the 63 kDa regulatory A subunits of the Mn2+-independent conventional protein phosphatase in human erythrocyte cytosol, respectively. Reconstitution of C'A and CA' revealed that the metal dependency resided in C' and not in A'. In CA, 0.87±0.12 mol zinc and 0.35±0.18 mol iron per mol enzyme were detected by atomic absorption spectrophotometry, but manganese, magnesium and cobalt were not detected. None of these metals was detected in C'A'. Pre-incubation of C' with ZnCl2 and FeCl2, but not FeCl3, synergistically stimulated the Mn2+-independent protein phosphatase activity. The protein phosphatase activity of C was unaffected by the same zinc and/or iron treatment. These results suggest that C is a Zn2+- and Fe2+-metalloenzyme and that C' is the apoenzyme. Copyright (C) 1999 Federation of European Biochemical Societies.

Original languageEnglish
Pages (from-to)29-33
Number of pages5
JournalFEBS Letters
Issue number1
Publication statusPublished - 1999 Mar 19


  • Human erythrocyte
  • Iron
  • Metal analysis
  • Mn dependency
  • Protein phosphatase 2A
  • Zinc

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology


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