Activation of protein phosphatase 2A by cAMP-dependent protein kinase- catalyzed phosphorylation of the 74-kDa B' (δ) regulatory subunit in vitro and identification of the phosphorylation sites

Hirofumi Usui, Rintaro Inoue, Osamu Tanabe, Yasumasa Nishito, Masahiro Shimizu, Hideyuki Hayashi, Hiroyuki Kagamiyama, Masao Takeda

Research output: Contribution to journalArticlepeer-review

73 Citations (Scopus)

Abstract

Human erythrocyte protein phosphatase 2A, which comprises a 34-kDa catalytic C subunit, a 63-kDa regulatory A subunit and a 74-kDa regulatory B'' (δ) subunit, was phosphorylated at serine residues of B'' in vitro by cAMP-dependent protein kinase (A-kinase). In the presence and absence of 0.5 μM okadaic acid (OA), A-kinase gave maximal incorporation of 1.7 and 1.0 mol of phosphate per mol of B'', respectively. The K(m) value of A-kinase for CAB'' was 0.17 ± 0.01 μM in the presence of OA. The major in vitro phosphorylation sites of B'' were identified as Ser-60, -75 and -573 in the presence of OA, and Ser-75 and -573 in the absence of OA. Phosphorylation of B'' did not dissociate B'' from CA, and stimulated the molecular activity of CAB'' toward phosphorylated H1 and H2B histones, 3.8- and 1.4-fold, respectively, but not toward phosphorylase a.

Original languageEnglish
Pages (from-to)312-316
Number of pages5
JournalFEBS Letters
Volume430
Issue number3
DOIs
Publication statusPublished - 1998 Jul 3

Keywords

  • 74-kDa regulatory subunit
  • Human erythrocyte
  • Phosphorylation sites
  • Protein phosphatase 2A
  • cAMP-dependent protein kinase

ASJC Scopus subject areas

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

Fingerprint Dive into the research topics of 'Activation of protein phosphatase 2A by cAMP-dependent protein kinase- catalyzed phosphorylation of the 74-kDa B' (δ) regulatory subunit in vitro and identification of the phosphorylation sites'. Together they form a unique fingerprint.

Cite this