Copper/zinc superoxide dismutase is phosphorylated and modulated specifically by granulocyte-colony stimulating factor in myeloid cells

Abstract

Using two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (2-D SDS-PAGE) of 32P-labeled cytosolic and membrane extracts, we identified a 21.5 kDa phosphoprotein with an isoelectric point of 6.0 in NFS-60 cells that was phosphorylated maximally at 15 min by treatment with granulocyte-colony stimulating factor (G-CSF) but not with interlevkin-3 (IL-3) or colony-stimulating factor-1 (macrophage-colony stimulating factor (CSF-1 (M-CSF)). The phosphorylation of this protein, designated 21.5/6.0, was unaffected by a series of antiproliferative agents [32]. These findings suggested that the 21.5/6.0 phosphoprotein may be involved in specific G-CSF-mediated biological responses..