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Granulocyte colony‐stimulating factor‐induced dephosphorylation of a 45 kD cytosolic protein in HL‐60 cells differentiating into neutrophils
Author(s) -
Yamaguchi Teruhide,
Oshizawa Tadashi,
Yamaguchi Takamasa,
Suzuki Kazuhiro,
Yamamoto Yukio,
Hayakawa Takao
Publication year - 1998
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1046/j.1365-2141.1998.00829.x
Subject(s) - phosphoprotein , dephosphorylation , phosphorylation , staurosporine , microbiology and biotechnology , protein kinase a , cytosol , kinase , serine , protein kinase c , granulocyte , biochemistry , protein phosphorylation , phosphatase , biology , chemistry , immunology , enzyme
Granulocyte colony‐stimulating factor (G‐CSF)‐induced alteration of phosphoprotein during differentiation of HL‐60 cells was studied. From the two‐dimensional gel electrophoresis analysis of phosphoproteins, a 45 kD phosphoprotein in the cytosolic fraction of DMSO‐pretreated HL‐60 cells was rapidly dephosphorylated by the addition of G‐CSF. This 45 kD phosphoprotein migrated into four or five spots between 4.5 and 5.5 pI. The dephosphorylation of 45 kD protein was observed within at least 10 min and reached a maximum at 60 min. Phosphoamino acid analysis showed that only serine residue of 45 kD phosphoprotein was phosphorylated, suggesting that G‐CSF induced an activation of serine phosphatase. Furthermore, Staurosporine and calphostin C inhibited the phosphorylation of 45 kD protein, suggesting that protein kinase C or its downstream kinase(s) is involved in the phosphorylation of 45 kD protein. These results indicate that G‐CSF causes dephosphorylation of a 45 kD cytosolic phosphoprotein which may play a role in signal transduction of G‐CSF.