Isoform specific phosphorylation of protein phosphatase 2C expressed in COS7 cells.
Of the six distinct isoforms of mouse protein phosphatase 2C (PP2C) (alpha, beta-1, beta-2, beta-3, beta-4 and beta-5), PP2C alpha was specifically phosphorylated on the serine residue(s) when expressed in COS7 cells. Analysis of phosphorylation sites using site-directed mutagenesis demonstrated that Ser-375 and/or Ser-377 were phosphorylated in vivo. These serine residues were the sites of phosphorylation by casein kinase II in vitro. Phosphorylation of PP2C alpha was enhanced two-fold by the addition of okadaic acid to the culture medium, but addition of cyclosporin A had no such effect. These results suggest that the expressed PP2C alpha is phosphorylated by a casein kinase II-like protein kinase and dephosphorylated by PP1 and/or PP2A in COS7 cells.
Department of Biochemistry, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan.
T
T
Kobayashi
K
K
Kusuda
M
M
Ohnishi
H
H
Wang
S
S
Ikeda
M
M
Hanada
Y
Y
Yanagawa
S
S
Tamura
D000818:Animals; D019556:COS Cells / Q000201:enzymology*; D047390:Casein Kinase II; D016572:Cyclosporine / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D016297:Mutagenesis, Site-Directed; D019319:Okadaic Acid / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D054648:Protein Phosphatase 2; D000071636:Protein Phosphatase 2C; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D012694:Serine / Q000378:metabolism*
D004791:Enzyme Inhibitors; D007527:Isoenzymes; D029701:Saccharomyces cerevisiae Proteins; D019319:Okadaic Acid; D012694:Serine; D016572:Cyclosporine; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases; C087358:PTC1 protein, S cerevisiae; D010749:Phosphoprotein Phosphatases; C000607466:Ppm1a protein, mouse; D054648:Protein Phosphatase 2; D000071636:Protein Phosphatase 2C