Studies on functions of the 63-kDa A- and 74-kDa B'(δ)-regulatory subunits in human erythrocyte protein phosphatase 2A: Dissociation and reassociation of the subunits

Rintaro Inoue, Hirofumi Usui, Osamu Tanabe, Yasumasa Nishito, Masahiro Shimizu, Masao Takeda

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

A heterodimeric form, CA, of protein-serine/threonine phosphatase (PP) 2A purified from human erythrocytes was dissociated into a 34-kDa catalytic subunit C and 63-kDa inactive subunit A by Sephacryl S-200 gel filtration in the presence of 6 M urea. Reassociation of the C- and A-subunits in the absence of urea suppressed the PP activity of the C subunit toward phosphorylase α, P-H2B histone, and P-H1 histone in the presence or absence of 20 mM MnCl2 or 50 mM Mg(CH3COO)2, but stimulated the PP activity toward P-H1 histone in the presence of 200 mM NaCl and the Mn2+-dependent protein- tyrosine phosphatase (PTP) activity toward P-Tyr-Glu copolymers. The 74-kDa inactive B'(δ) subunit was isolated from a heterotrimeric form, CAB'(δ), of PP2A partially purified from human erythrocytes, by heparin-Sepharose column chromatography. The B'(δ) subunit reassociated with CA and suppressed the PP- and PTP-activities of CA. The B'(δ) subunit did not associate with the isolated C subunit directly, and had no effect on the activities of the C subunit, indicating that the A subunit is essential for the association of the B'(δ) subunit with CA and the resulting suppression of the PP- and PTP- activities.

Original languageEnglish
Pages (from-to)1127-1135
Number of pages9
JournalJournal of biochemistry
Volume126
Issue number6
DOIs
Publication statusPublished - 1999 Jan 1

Keywords

  • 74-kDa regulatory subunit B'(δ), 63-kDa regulatory subunit A
  • Human erythrocytes
  • Protein-serine/threonine phosphatase 2A
  • Reconstruction of subunits

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology

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