Dual modulation of phosphorylation of a 60 kDa nuclear protein in interferon-alpha treated Daudi cells.
To explore the modulation of phosphorylation and/or kinase activity of cellular proteins in interferon-alpha (IFN-alpha) treated Daudi cells, experiments were performed to determine the effect of IFN-alpha on the ability of cellular proteins to undergo autophosphorylation reaction in-vitro. Treatment of cells with IFN-alpha significantly inhibited the amount of phosphorylation of a nuclear protein of about 60 kDa [+/- 3000 KDa, (P60)]. Results of phosphoamino acids analysis indicated that the nuclear P60 was a phosphotyrosine containing protein and was predominantly phosphorylated on threonine and serine in the absence of IFN-alpha. Treatment with IFN-alpha had a dual effect on relative phosphoamino acids content of P60: inhibited the phosphorylation on threonine residue, and enhanced the phosphorylation on serine and tyrosine residues. The nuclear P60 is not one of earlier described IFN-responsive signaling protein as it was not translocated from the cytosol.
Kumar
R
R
Department of Medicine, Pennsylvania State University College of Medicine, Hershey 17033.
D001402:B-Lymphocytes / Q000378:metabolism*; D002460:Cell Line; D006801:Humans; D000077190:Interferon alpha-2; D016898:Interferon-alpha / Q000494:pharmacology*; D008970:Molecular Weight; D009687:Nuclear Proteins / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D010769:Phosphothreonine / Q000378:metabolism; D019000:Phosphotyrosine; D011994:Recombinant Proteins; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
D000077190:Interferon alpha-2; D016898:Interferon-alpha; D009687:Nuclear Proteins; D010750:Phosphoproteins; D011994:Recombinant Proteins; D010769:Phosphothreonine; D010768:Phosphoserine; D019000:Phosphotyrosine; D014443:Tyrosine