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

研究成果: Article査読

73 被引用数 (Scopus)

抄録

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.

本文言語English
ページ(範囲)312-316
ページ数5
ジャーナルFEBS Letters
430
3
DOI
出版ステータスPublished - 1998 7 3

ASJC Scopus subject areas

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

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