TY - JOUR
T1 - 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
AU - Usui, Hirofumi
AU - Inoue, Rintaro
AU - Tanabe, Osamu
AU - Nishito, Yasumasa
AU - Shimizu, Masahiro
AU - Hayashi, Hideyuki
AU - Kagamiyama, Hiroyuki
AU - Takeda, Masao
N1 - Funding Information:
We thank Mieko Kawamura and Ryoko Takemoto for their secretarial and technical assistance. This work was supported in part by grants-in-aid for Cancer Research and Scientific Research from the Ministry of Education, Science, Sports and Culture of Japan and by research grants from Fujisawa Foundation and Takeda Science Foundation.
PY - 1998/7/3
Y1 - 1998/7/3
N2 - 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.
AB - 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.
KW - 74-kDa regulatory subunit
KW - Human erythrocyte
KW - Phosphorylation sites
KW - Protein phosphatase 2A
KW - cAMP-dependent protein kinase
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U2 - 10.1016/S0014-5793(98)00684-X
DO - 10.1016/S0014-5793(98)00684-X
M3 - Article
C2 - 9688562
AN - SCOPUS:0032479215
VL - 430
SP - 312
EP - 316
JO - FEBS Letters
JF - FEBS Letters
SN - 0014-5793
IS - 3
ER -